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href="/article/%E6%B7%B1%E5%85%A5%E7%90%86%E8%A7%A3Proxy%E4%B8%8EReflect.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>深入理解Proxy与Reflect</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/article/%E6%B7%B1%E5%85%A5%E7%90%86%E8%A7%A3%E6%B5%8F%E8%A7%88%E5%99%A8%E7%BC%93%E5%AD%98%E6%9C%BA%E5%88%B6.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>深入理解浏览器缓存机制</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/article/%E6%B7%B1%E5%85%A5%E7%90%86%E8%A7%A3%E6%B5%8F%E8%A7%88%E5%99%A8%E8%BF%90%E8%A1%8C%E5%8E%9F%E7%90%86.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>深入理解浏览器运行原理</p><!--]--><!----></a><!----></div><!----></div><!--]--></div></section></div><div class="group" data-v-5081c0c7><section class="VPSidebarItem level-0" data-v-5081c0c7 data-v-79816cba><div class="item" role="button" tabindex="0" data-v-79816cba><div class="indicator" data-v-79816cba></div><h2 class="text" data-v-79816cba>学习笔记</h2><!----></div><div class="items" data-v-79816cba><!--[--><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/note/JavaScript.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>JavaScript基础</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/note/CSS.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>CSS基础</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/note/JavaScriptEnhanced.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>JavaScript进阶</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/note/Front-end%20Engineering.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>前端工程化</p><!--]--><!----></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-79816cba data-v-79816cba><div class="item" data-v-79816cba><div class="indicator" data-v-79816cba></div><a class="VPLink link link" href="/note/SSR.html" data-v-79816cba data-v-fd6e3585><!--[--><p class="text" data-v-79816cba>服务端渲染</p><!--]--><!----></a><!----></div><!----></div><!--]--></div></section></div><!--]--><!--[--><!--]--></nav></aside><div class="VPContent has-sidebar" id="VPContent" data-v-6305e88a data-v-435404df><div class="VPDoc has-sidebar has-aside" data-v-435404df data-v-25140dfd><!--[--><!--]--><div class="container" data-v-25140dfd><div class="aside" data-v-25140dfd><div class="aside-curtain" data-v-25140dfd></div><div class="aside-container" data-v-25140dfd><div class="aside-content" data-v-25140dfd><div class="VPDocAside" data-v-25140dfd data-v-2b53d15f><!--[--><!--]--><!--[--><!--]--><div class="VPDocAsideOutline" data-v-2b53d15f data-v-1cf492a7><div class="content" data-v-1cf492a7><div class="outline-marker" data-v-1cf492a7></div><div class="outline-title" data-v-1cf492a7>On this page</div><nav aria-labelledby="doc-outline-aria-label" data-v-1cf492a7><span class="visually-hidden" id="doc-outline-aria-label" data-v-1cf492a7> Table of Contents for current page </span><ul class="root" data-v-1cf492a7 data-v-e09875d9><!--[--><!--]--></ul></nav></div></div><!--[--><!--]--><div class="spacer" data-v-2b53d15f></div><!--[--><!--]--><!----><!--[--><!--]--><!--[--><!--]--></div></div></div></div><div class="content" data-v-25140dfd><div class="content-container" data-v-25140dfd><!--[--><!--]--><!----><main class="main" data-v-25140dfd><div style="position:relative;" class="vp-doc _note_React" data-v-25140dfd><div><h1 id="react" tabindex="-1">React <a class="header-anchor" href="#react" aria-label="Permalink to &quot;React&quot;">​</a></h1><h2 id="邂逅react" tabindex="-1">邂逅React <a class="header-anchor" href="#邂逅react" aria-label="Permalink to &quot;邂逅React&quot;">​</a></h2><h3 id="react开发依赖" tabindex="-1">React开发依赖 <a class="header-anchor" href="#react开发依赖" aria-label="Permalink to &quot;React开发依赖&quot;">​</a></h3><ul><li><code>react</code> 包含React的核心代码</li><li><code>react-dom</code> 将React渲染到不同平台需要的核心代码</li><li><code>babel</code> 将JSX转换成React代码的工具</li></ul><p>为什么要拆分成这么多的包？</p><ul><li>不同的库各司其职，让库变得纯粹</li><li><code>react</code>包中包含了 React Web 和 React Native 共同拥有的<strong>核心代码</strong></li><li><code>react-dom</code> 针对Web和Native完成的事情不同 <ul><li>Web端：<code>react-dom</code>会将JSX渲染成真实DOM，展示在浏览器中</li><li>Native端：<code>react-dom</code>会将JSX渲染成原生的控件（如Android中的Button，iOS中的UIButton）</li></ul></li></ul><h3 id="babel与react的关系" tabindex="-1">Babel与React的关系 <a class="header-anchor" href="#babel与react的关系" aria-label="Permalink to &quot;Babel与React的关系&quot;">​</a></h3><p>Babel是什么？</p><ul><li>Babel又名Babel.js</li><li>是目前前端使用非常广泛的编译器、转换器（Compiler/Transformer）</li><li>提供对ES6语法的Polyfill，将ES6语法转为大多数浏览器都支持的ES5语法</li></ul><p>二者之间的联系</p><ul><li>默认情况下React开发可以不使用Babel</li><li>但是我们不可能使用React.createElement来编写代码</li><li>通过Babel，我们可以直接编写JSX（JavaScript XML），让Babel帮我们转化为React.createElement</li></ul><h3 id="react初体验" tabindex="-1">React初体验 <a class="header-anchor" href="#react初体验" aria-label="Permalink to &quot;React初体验&quot;">​</a></h3><p>我们通过CDN方式引入react、react-dom、babel这三个依赖</p><p>并且创建<code>#root</code>根节点，作为渲染React组件的容器，再新建一个script标签，键入以下内容</p><div class="language-html line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">html</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">id</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">root</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">src</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">https://unpkg.com/react@18/umd/react.development.js</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">crossorigin</span><span style="color:#89DDFF;">&gt;&lt;/</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">src</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">https://unpkg.com/react-dom@18/umd/react-dom.development.js</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">crossorigin</span><span style="color:#89DDFF;">&gt;&lt;/</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">src</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">https://unpkg.com/babel-standalone@6/babel.min.js</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">crossorigin</span><span style="color:#89DDFF;">&gt;&lt;/</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">type</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">text/babel</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hello, React!</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;,</span><span style="color:#A6ACCD;"> document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">script</span><span style="color:#89DDFF;">&gt;</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>这时，一个内容为<code>Hello, React!</code>的div标签就被渲染到页面上了</p><p>需要注意的是：<code>ReactDOM.render</code>这种写法适用于React18之前，在React18之后建议用下面的代码渲染根节点：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hello, React!</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><h3 id="第一个react程序" tabindex="-1">第一个React程序 <a class="header-anchor" href="#第一个react程序" aria-label="Permalink to &quot;第一个React程序&quot;">​</a></h3><p>设想我们现在有这样一个需求：点击按钮使文本<code>Hello, World!</code>变为<code>Hello, React!</code></p><p>我们很容易就能写出如下代码：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> msg </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#676E95;font-style:italic;">// initial render</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">handleChangeClick</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">msg</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, React!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">handleChangeClick</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Text</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><p>在Vue中，如果我们对数据进行了修改，Vue的数据响应式会自动帮我们完成视图的更新</p><p>然而在React中，当我们修改了数据需要通知React，让React重新渲染视图。在这里，我们可以把渲染的过程封装为一个函数，方便我们重复调用，触发重新渲染</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> msg </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#676E95;font-style:italic;">// initial render</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">handleChangeClick</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">msg</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, React!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#82AAFF;">render</span><span style="color:#F07178;">() </span><span style="color:#676E95;font-style:italic;">// re-render</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#F07178;">(</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">handleChangeClick</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Text</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div><p>这个案例中，我们使用<code>{}</code>语法，将动态的JS语法嵌入到JSX代码中</p><h3 id="组件化开发" tabindex="-1">组件化开发 <a class="header-anchor" href="#组件化开发" aria-label="Permalink to &quot;组件化开发&quot;">​</a></h3><p>React有两种组件：类组件与函数组件，React18+推荐使用函数组件+Hooks</p><h4 id="类组件" tabindex="-1">类组件 <a class="header-anchor" href="#类组件" aria-label="Permalink to &quot;类组件&quot;">​</a></h4><p>我们使用类组件来逐步重构上面的案例：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;{this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><ul><li><p>类组件必须实现render方法，render方法返回值为后续React渲染到页面的内容</p></li><li><p>组件内数据分为两类</p><ul><li>参与页面更新的数据 <ul><li>当数据变化时，需要触发组件重新渲染</li></ul></li><li>不参与页面更新的数据 <ul><li>数据不会变化，或变化后也不需要重新渲染视图</li></ul></li></ul></li><li><p>需要触发视图重新渲染的数据，我们将其成为：<strong>参与数据流</strong></p><ul><li>定义在对象的<code>state</code>属性中</li><li>可以通过在构造函数中通过 <code>this.state = { name: &#39;Ziu&#39; }</code> 来定义状态</li><li>当数据发生变化，可以调用 <code>this.setState</code> 来更新数据，通知React执行视图更新</li><li>update操作时，会重新调用render函数，使用最新的数据来渲染界面</li></ul></li></ul><p>:::success 需要注意的是，在constructor中我们调用了<code>super</code>，因为App类是继承自React.Component类，调用<code>super</code>即调用了其父类的构造函数，让我们的App组件可以继承一些内置属性/方法如<code>state setState render</code> :::</p><p>至此我们完成了数据的迁移，下面我们来完成事件函数的迁移。</p><p>有了之前的介绍，我们很容易的可以写出下面的代码：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeText</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, React!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;{this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeText</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Text</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><p>我们可以写一个实例方法changeText来修改msg，然而，此时我们点击按钮后发现，案例不能正常工作。</p><p>如果在changeText中打log，会发现函数被正常触发了，但是状态没有更新</p><p>为什么this.setState失效了？这和this的绑定有关：绑定的<code>changeText</code>在被调用时，向上找<code>this</code>找到的是全局的<code>this</code>即<code>undefined</code></p><p>这种情况有点类似于下面的例子：</p><div class="language-ts line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">ts</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> app </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">new</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">App</span><span style="color:#A6ACCD;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">app</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">changeText</span><span style="color:#A6ACCD;">() </span><span style="color:#676E95;font-style:italic;">// this =&gt; app</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> func </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> app</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">changeText</span></span>
<span class="line"><span style="color:#82AAFF;">func</span><span style="color:#A6ACCD;">() </span><span style="color:#676E95;font-style:italic;">// this =&gt; undefined</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>在非严格模式下，直接调用func时的this指向的是window，严格模式下则为undefined</p><p>为了解决this绑定的问题，我们需要显式把函数调用绑定给当前组件，这时组件就可以正常工作了。</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeText</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, React!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;{this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeText</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">this</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Text</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><h3 id="提前绑定this" tabindex="-1">提前绑定this <a class="header-anchor" href="#提前绑定this" aria-label="Permalink to &quot;提前绑定this&quot;">​</a></h3><p>在render函数中频繁通过<code>.bind</code>毕竟不太优雅，好在也有另一种方式：可以在constructor中提前对实例方法进行this绑定：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#82AAFF;">constructor</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> msg</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, World!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">changeText</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">changeText</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeText</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Text</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h3 id="列表渲染" tabindex="-1">列表渲染 <a class="header-anchor" href="#列表渲染" aria-label="Permalink to &quot;列表渲染&quot;">​</a></h3><p>可以通过循环，将数组渲染到视图中</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> movieList</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">The Shawshank Redemption</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">The Godfather</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">The Godfather: Part II</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">The Dark Knight</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> ]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">movieList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">item</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">item</span><span style="color:#89DDFF;">}&gt;{</span><span style="color:#A6ACCD;">item</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br></div></div><p>需要注意的是，这里绑定的key的功能类似于Vue中的特殊属性key，它用来帮助React对列表渲染进行更高效的更新。</p><h3 id="计数器案例" tabindex="-1">计数器案例 <a class="header-anchor" href="#计数器案例" aria-label="Permalink to &quot;计数器案例&quot;">​</a></h3><p>结合之前的知识，可以实现一个简单的计数器</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">subCount</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">subCount</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">addCount</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">+</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">subCount</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">-</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Add</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">subCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Sub</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br></div></div><h2 id="认识jsx语法" tabindex="-1">认识JSX语法 <a class="header-anchor" href="#认识jsx语法" aria-label="Permalink to &quot;认识JSX语法&quot;">​</a></h2><ul><li>认识JSX语法</li><li>JSX基本使用</li><li>JSX事件绑定</li><li>JSX条件渲染</li><li>JSX列表渲染</li><li>JSX的原理与本质</li></ul><p>是因为我们给script标签添加了<code>type=&quot;text/babel&quot;</code>属性，浏览器不会对这个script进行解析，当babel被加载完成后，babel会在页面中寻找<code>type=&quot;text/babel&quot;</code>的script标签进行转义，转义后的代码才会被浏览器执行</p><ul><li>JSX: JavaScript Extension / JavaScript XML</li><li>All in JS</li><li>不同于Vue的模板语法 不需要专门学习模板语法中的指令(v-for/v-if/v-bind)</li></ul><h3 id="jsx的使用" tabindex="-1">JSX的使用 <a class="header-anchor" href="#jsx的使用" aria-label="Permalink to &quot;JSX的使用&quot;">​</a></h3><h4 id="书写jsx的规范与注意事项" tabindex="-1">书写JSX的规范与注意事项 <a class="header-anchor" href="#书写jsx的规范与注意事项" aria-label="Permalink to &quot;书写JSX的规范与注意事项&quot;">​</a></h4><ul><li>JSX的顶层只能有一个根元素 元素必须包裹在单独的闭合标签中 <ul><li>后续会接触到Fragment标签 Vue3也是将元素包裹在了Fragments标签中</li></ul></li><li>为了方便阅读 通常在JSX外层包裹一个小括号<code>()</code>方便阅读</li></ul><h4 id="jsx的注释" tabindex="-1">JSX的注释 <a class="header-anchor" href="#jsx的注释" aria-label="Permalink to &quot;JSX的注释&quot;">​</a></h4><p>在JSX中编写注释，需要以<code>{/* ... */}</code>的形式，在<code>.jsx/.tsx</code>文件中，通过快捷键就可以快捷的生成注释内容</p><p>本质上是通过花括号语法<code>{}</code>嵌入了一段JavaScript表达式，在表达式中书写注释</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#676E95;font-style:italic;">/* Some Comment... */</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Add</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">subCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Sub</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;">)</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h4 id="jsx嵌入变量作为子元素" tabindex="-1">JSX嵌入变量作为子元素 <a class="header-anchor" href="#jsx嵌入变量作为子元素" aria-label="Permalink to &quot;JSX嵌入变量作为子元素&quot;">​</a></h4><p>可以通过花括号语法将变量内容嵌入到JSX语法中：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> message </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hello, React!</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> arr </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> [</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">abc</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">cba</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">nba</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">]</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;"> message </span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;"> arr </span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><ul><li>变量类型为number string array类型时，可以直接展示</li><li>变量类型为null undefined boolean类型时，内容为空 <ul><li>如果希望可以展示null/undefined/boolean类型，需要通过<code>.toString()</code>方法将其转为字符串</li><li>空字符串拼接、String构造函数等方式</li></ul></li><li>Object对象类型不能作为子元素 (Objects are not valid as a React child)</li></ul><p>下例中，只有number类型会被正常展示，而其余变量则不会展示在视图中</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">number</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">123</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">n</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">null</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">u</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">undefined</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">b</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">true</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Number: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">number</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Null: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">n</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Undefined: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">u</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Boolean: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">b</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br></div></div><p>将对象类型变量嵌入到JSX语法中，React会抛出错误：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">obj</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Ziu</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> obj </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h4 id="jsx的属性绑定" tabindex="-1">JSX的属性绑定 <a class="header-anchor" href="#jsx的属性绑定" aria-label="Permalink to &quot;JSX的属性绑定&quot;">​</a></h4><ul><li>在Vue中我们通过<code>v-bind</code>绑定属性</li><li>在React中如何绑定元素属性？</li><li><code>title</code> <code>src</code> <code>href</code> <code>class</code> 内联<code>style</code>等</li></ul><p>下例中，我们通过花括号语法对元素的属性进行了动态绑定，点击按钮可以切换className状态</p><p>同时，动态绑定的内联样式也会发生改变，通过花括号语法动态绑定style属性</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isActive</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">false</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> title</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Description</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">changeActive</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">changeActive</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeActive</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isActive</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isActive</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isActive</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">title</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">classList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">title</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isActive</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">?</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">active</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#F07178;">]</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">classList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">join</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">title</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">color</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> isActive </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">blue</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Hello, React!</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeActive</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br></div></div><p>当我们通过脚手架创建项目时，可以使用第三方库来帮我们完成className的绑定</p><ul><li><code>classnames</code>库 <code>pnpm add classnames</code></li><li>提供了多种创建className的语法</li></ul><h3 id="jsx事件绑定" tabindex="-1">JSX事件绑定 <a class="header-anchor" href="#jsx事件绑定" aria-label="Permalink to &quot;JSX事件绑定&quot;">​</a></h3><p>先前的例子中，我们已经通过<code>onClick</code>给按钮绑定过事件处理函数了，其中涉及了this绑定</p><p>回顾一下this的四种绑定规则：</p><ol><li>默认绑定 独立执行 foo() this =&gt; undefined</li><li>隐式绑定 被一个对象执行 obj.foo() this =&gt; obj</li><li>显式绑定 call/bind/apply foo.call(&#39;aaa&#39;) this =&gt; String(&#39;aaa&#39;)</li><li>new绑定 new Foo() 创建一个新对象，并且赋值给this</li></ol><p>除了之前通过<code>function + bind</code>绑定事件处理函数的方式，还可以通过箭头函数来帮我们完成处理</p><p>箭头函数的内部使用this时会自动向上层作用域查找this 实际开发中这种方式并不常用</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line highlighted"><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isActive</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isActive</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>相比之下更推荐使用的，是下面这种方式：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line highlighted"><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p>这样书写有几种好处：</p><ul><li>给事件处理函数传递参数更方便</li><li>书写更方便 不必主动考虑this绑定问题</li></ul><p>它的原理是，我们对外暴露的本质上是一个箭头函数，当调用箭头函数时，本质上是执行<code>this.changeActive</code>，这是 一种隐式绑定，找到的this为当前组件实例</p><h3 id="事件绑定参数传递" tabindex="-1">事件绑定参数传递 <a class="header-anchor" href="#事件绑定参数传递" aria-label="Permalink to &quot;事件绑定参数传递&quot;">​</a></h3><ul><li>Event参数传递</li><li>额外参数传递</li></ul><p>事件回调函数的第一个默认参数就是Event对象，这个Event对象是经过React包装后的，但是原生的属性都包含在内，React对其进行了一些扩展</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">(ev) </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Event</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">ev</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#676E95;font-style:italic;">/* event将作为默认入参传递给changeActive */</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeActive</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#676E95;font-style:italic;">/* 通过箭头函数绑定事件监听回调函数时 需要手动透传一下event */</span><span style="color:#89DDFF;">}</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={(</span><span style="color:#A6ACCD;font-style:italic;">ev</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">(ev)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div><p>当我们需要传递额外的参数时，通过箭头函数传递也更容易：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">(ev</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> name</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> age) </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Event</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">ev</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Name</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">name</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Age</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">age</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#676E95;font-style:italic;">/* NOT Recommand */</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeActive</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">bind</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">this,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Ziu</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">18</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#676E95;font-style:italic;">/* Recommand */</span><span style="color:#89DDFF;">}</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={(</span><span style="color:#A6ACCD;font-style:italic;">ev</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">(ev</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Ziu</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">18</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change Active</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br></div></div><p>需要注意，当通过<code>.bind</code>传递额外参数时，最后一个参数才是默认传递的Event对象，这会导致非预期行为</p><div class="language-sh line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">sh</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> Event </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Ziu</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> Name </span><span style="color:#F78C6C;">18</span></span>
<span class="line"><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> Age </span><span style="color:#89DDFF;">{</span><span style="color:#FFCB6B;">Event</span><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h3 id="jsx事件绑定案例" tabindex="-1">JSX事件绑定案例 <a class="header-anchor" href="#jsx事件绑定案例" aria-label="Permalink to &quot;JSX事件绑定案例&quot;">​</a></h3><p>创建一个Tab栏，选中哪个选项，哪个选项被激活切换为红色，同一时间仅有一个激活项目</p><p>结合之前学习的内容，很容易就可以写出下述 代码：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> tabList</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Recommend</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hot</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">User</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeActive</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">index</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">tabs</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">item</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">={</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">tab </span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">+</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">active</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">color</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">black</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">index</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeActive</span><span style="color:#A6ACCD;">(index)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">item</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br></div></div><h3 id="条件渲染" tabindex="-1">条件渲染 <a class="header-anchor" href="#条件渲染" aria-label="Permalink to &quot;条件渲染&quot;">​</a></h3><p>控制元素按照某种条件渲染，以加载状态为例</p><p>列表未加载出来时，展示<code>加载中</code>，加载完毕则渲染完整内容：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isLoading</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">true</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeLoading</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isLoading</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isLoading</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isLoading</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">isLoading </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">loading</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> Loading ... </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ) </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">list</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Some Content</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> )</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeLoading</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Toggle Loading</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br></div></div><p>常用的条件渲染方式</p><ul><li><code>if/else/else-if</code><ul><li>适合判断逻辑较复杂的情况 将条件渲染抽离出来</li></ul></li><li>三元运算符 <code>?:</code><ul><li>适合判断逻辑简单的情况</li></ul></li><li>逻辑与运算符 <code>&amp;&amp;</code><ul><li>如果条件成立则渲染某个组件，否则什么内容都不渲染</li></ul></li><li>可选链 <code>user?.info?.name</code></li></ul><p>下例中通过逻辑与运算符<code>&amp;&amp;</code>决定<code>VIP</code>标签是否展示在视图中</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isVip</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">false</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeVip</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isVip</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isVip</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isVip</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">class</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">user</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">username: Ziu</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">isVip </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">vip-banner</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> VIP </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeVip</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Toggle Vip</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br></div></div><h4 id="在react中简单写一个-v-show" tabindex="-1">在React中简单写一个&quot;v-show&quot; <a class="header-anchor" href="#在react中简单写一个-v-show" aria-label="Permalink to &quot;在React中简单写一个&quot;v-show&quot;&quot;">​</a></h4><p><code>v-show</code>是Vue提供的语法糖，不同于<code>v-if</code>，它只切换元素的<code>display</code>属性。</p><p>下面我们在React中简单复现一个<code>v-show</code>的效果：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isShow</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">true</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeShow</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> isShow</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isShow</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isShow</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">display</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> isShow </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">none</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}&gt;</span><span style="color:#A6ACCD;">Target Element</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeShow</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Toggle Show</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br></div></div><p>实际使用中，将其封装为hooks来调用更具通用性，也更方便管理</p><h3 id="列表渲染中的高阶函数" tabindex="-1">列表渲染中的高阶函数 <a class="header-anchor" href="#列表渲染中的高阶函数" aria-label="Permalink to &quot;列表渲染中的高阶函数&quot;">​</a></h3><ul><li><code>filter</code>函数 过滤器</li><li><code>slice</code>函数 分页</li><li><code>sorc</code>函数 排序</li><li>...</li></ul><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> stuList</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Ziu</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> age</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">18</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> score</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">88</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Kobe</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> age</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">19</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> score</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">59</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Why</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> age</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">20</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> score</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">61</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">James</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> age</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">21</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> score</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">99</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> ]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">stuList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// 及格的学生</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">passStuList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">stuList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">filter</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">item</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">item</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">score</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&gt;=</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">60</span><span style="color:#F07178;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// 分数最高的两个学生</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">top2StuList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">stuList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">sort</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">a</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">b</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">b</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">score</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">-</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">a</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">score</span><span style="color:#F07178;">)</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">slice</span><span style="color:#F07178;">(</span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">2</span><span style="color:#F07178;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">list</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">stuList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">({</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">name</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">age</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">score</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">})</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">item</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">name</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">age</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">age</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">score</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">score</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br></div></div><h3 id="jsx的本质" tabindex="-1">JSX的本质 <a class="header-anchor" href="#jsx的本质" aria-label="Permalink to &quot;JSX的本质&quot;">​</a></h3><h4 id="jsx的转换过程" tabindex="-1">JSX的转换过程 <a class="header-anchor" href="#jsx的转换过程" aria-label="Permalink to &quot;JSX的转换过程&quot;">​</a></h4><p>假设我们有下面的JSX代码：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">page</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">page</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">header</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Header</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">content</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> Content</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">banner</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Banner</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Item 1</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Item 2</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Item 3</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Item 4</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Item 5</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">footer</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Footer</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">page</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">page</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br></div></div><p>通过JSX语法描述出来的template会经过Babel转化，转化为JavaScript树的数据结构</p><p>在控制台中我们可以看到，子节点都存放进了父节点的<code>props.children</code>中</p><h4 id="虚拟dom树" tabindex="-1">虚拟DOM树 <a class="header-anchor" href="#虚拟dom树" aria-label="Permalink to &quot;虚拟DOM树&quot;">​</a></h4><p>JSX仅仅是<code>React.createElement(component, props, ...children)</code>的语法糖</p><p>所有的JSX语法都会被Babel转化为这样的命令式语法</p><p>.createElement函数的参数</p><ul><li>type <ul><li>当前ReactElement的类型</li><li>如果是标签元素，值为字符串如：<code>&quot;div&quot;</code></li><li>如果是组件元素，那么值为组件的名称</li></ul></li><li>config <ul><li>所有JSX中绑定的属性都在config中以键值对的形式存储</li><li>例如<code>className</code> =&gt; <code>class</code></li></ul></li></ul><p>我们借助Babel官网的Playground来检查一下JSX语法的转化</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">jsx</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">as</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">_jsx</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">react/jsx-runtime</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">jsxs</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">as</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">_jsxs</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">react/jsx-runtime</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> page </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsxs</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">div</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">className</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">page</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> [</span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">div</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">className</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">header</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Header</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsxs</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">div</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">className</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">content</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> [</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Content</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">div</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">className</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">banner</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Banner</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsxs</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">ul</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> [</span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">li</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Item 1</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">li</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Item 2</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">li</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Item 3</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">li</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Item 4</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">li</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Item 5</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)]</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)]</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">/*#__PURE__*/</span><span style="color:#82AAFF;">_jsx</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">div</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">className</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">footer</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">children</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Footer</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)]</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(page)</span><span style="color:#89DDFF;">;</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br></div></div><p>这时经过Babel转义后的纯JS函数，这段函数可以在浏览器中直接运行</p><p>如果移除了相关JSX代码，并将他们都替换为<code>React.createElement</code>函数调用，那么得到的代码也可以直接在浏览器中运行。Babel帮助我们完成了转化，提高了开发效率，相比于通过调用<code>React.createElement</code>来描述视图，通过JSX编写的代码更加容易维护</p><p>这些代码最终形成的就是虚拟DOM树，React可以将虚拟DOM渲染到页面上，形成真实DOM</p><p>虚拟DOM允许React可以通过diff算法，高效地对真实DOM树进行更新</p><h3 id="声明式编程" tabindex="-1">声明式编程 <a class="header-anchor" href="#声明式编程" aria-label="Permalink to &quot;声明式编程&quot;">​</a></h3><ul><li>虚拟DOM帮我们从命令式编程转到了声明式编程的模式</li><li>对虚拟DOM作何处理，如何渲染是由React决定的，由于做了一层抽象，那么同样可以将虚拟DOM渲染成原生组件（React Native）</li></ul><h3 id="购物车案例" tabindex="-1">购物车案例 <a class="header-anchor" href="#购物车案例" aria-label="Permalink to &quot;购物车案例&quot;">​</a></h3><p>下面写一个经典的购物车案例</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">formatPrice</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">price</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">`</span><span style="color:#C3E88D;">$ </span><span style="color:#89DDFF;">${</span><span style="color:#A6ACCD;">price</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">toFixed</span><span style="color:#A6ACCD;">(</span><span style="color:#F78C6C;">2</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}`</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">React</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> books</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">book1</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> author</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">author1</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> price</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">100</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">book2</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> author</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">author2</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> price</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">200</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">book3</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> author</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">author3</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> price</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">300</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">book4</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> author</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">author4</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> price</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">400</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> ]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeCount</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">count</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;">]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;">[</span><span style="color:#A6ACCD;">index</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">+=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">removeItem</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;">]</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">splice</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">index</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">getTotal</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">reduce</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">acc</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">price</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">})</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">acc</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">+</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">price</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">*</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">renderBookCart</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">books</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">total</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">getTotal</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">shopping-cart</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Shopping Cart</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">books</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">books</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">({</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">name</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">author</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">price</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">count</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">},</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">book</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">idx</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">index </span><span style="color:#89DDFF;">+</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">1</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">name</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">author</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">author</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">price</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#82AAFF;">formatPrice</span><span style="color:#A6ACCD;">(price)</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">counter</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeCount</span><span style="color:#A6ACCD;">(index</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-</span><span style="color:#F78C6C;">1</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">disabled</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">count </span><span style="color:#89DDFF;">&lt;=</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> -</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">counter-number</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">changeCount</span><span style="color:#A6ACCD;">(index</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">1</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">+</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">removeItem</span><span style="color:#A6ACCD;">(index)</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Delete</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">total</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Total: </span><span style="color:#89DDFF;">{</span><span style="color:#82AAFF;">formatPrice</span><span style="color:#A6ACCD;">(total)</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">renderEmptyTip</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">empty</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Shopping Cart is Empty</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">isEmpty</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">books</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">length</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">===</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!</span><span style="color:#A6ACCD;">isEmpty</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">?</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">renderBookCart</span><span style="color:#F07178;">() </span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">renderEmptyTip</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br><span class="line-number">62</span><br><span class="line-number">63</span><br><span class="line-number">64</span><br><span class="line-number">65</span><br><span class="line-number">66</span><br><span class="line-number">67</span><br><span class="line-number">68</span><br><span class="line-number">69</span><br><span class="line-number">70</span><br><span class="line-number">71</span><br><span class="line-number">72</span><br><span class="line-number">73</span><br><span class="line-number">74</span><br><span class="line-number">75</span><br><span class="line-number">76</span><br><span class="line-number">77</span><br><span class="line-number">78</span><br><span class="line-number">79</span><br><span class="line-number">80</span><br><span class="line-number">81</span><br><span class="line-number">82</span><br></div></div><h2 id="react项目开发" tabindex="-1">React项目开发 <a class="header-anchor" href="#react项目开发" aria-label="Permalink to &quot;React项目开发&quot;">​</a></h2><ul><li>认识脚手架工具</li><li>create-react-app</li><li>创建React项目</li><li>Webpack的配置</li></ul><h3 id="react脚手架" tabindex="-1">React脚手架 <a class="header-anchor" href="#react脚手架" aria-label="Permalink to &quot;React脚手架&quot;">​</a></h3><p>类似于Vue提供的 <code>pnpm create vite</code> 创建一个模板，React也可以通过 <code>create-react-app</code> 来初始化一个空的React模板</p><div class="language-sh line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">sh</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#FFCB6B;">pnpm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">add</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">create-react-app</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">-g</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># 全局安装create-react-app</span></span>
<span class="line"><span style="color:#FFCB6B;">create-react-app</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">react-app</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># 创建一个名为react-app的React项目</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;"># 删除node_modules package-lock.json</span></span>
<span class="line"><span style="color:#82AAFF;">cd</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">react-app</span></span>
<span class="line"><span style="color:#FFCB6B;">pnpm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">i</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># 使用pnpm重新安装依赖</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// index.js</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> ReactDOM </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react-dom/client</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> App </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./App</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> root </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> ReactDOM</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">createRoot</span><span style="color:#A6ACCD;">(document</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">querySelector</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">#root</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">))</span></span>
<span class="line"><span style="color:#A6ACCD;">root</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> /&gt;</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hello, React!</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><h2 id="react组件化开发" tabindex="-1">React组件化开发 <a class="header-anchor" href="#react组件化开发" aria-label="Permalink to &quot;React组件化开发&quot;">​</a></h2><ul><li>React组件生命周期</li><li>React组件间通信</li><li>React组件插槽</li><li>React非父子的通信</li><li>setState使用详解</li></ul><p>组件化是React的核心思想之一，组件化是一个抽象的过程，将大的应用程序抽象为多个小的组件，最终形成组件树</p><p>分而治之，让代码更容易组织和管理</p><p>React组件相对于Vue更加灵活多样，按照不同的方式可以分为多种组件</p><ul><li>根据组件定义方式，可以分为：函数组件(Functional Component)与类组件(Class Component)</li><li>根据组件内部是否有状态需要维护，可以分为：无状态组件(Stateless Component)和有状态组件(Stateful Component)</li><li>根据组件的不同职责，可以分为：展示型组件(Presentational Component)和容器型组件(Container Component)</li></ul><p>除此之外，还有异步组件、高阶组件等...</p><h3 id="类组件-1" tabindex="-1">类组件 <a class="header-anchor" href="#类组件-1" aria-label="Permalink to &quot;类组件&quot;">​</a></h3><ul><li>类组件的定义有以下要求： <ul><li>组件的名称必须为大写（无论是类组件还是函数组件）</li><li>类组件需要继承自React.Component</li><li>类组件内必须实现render函数</li></ul></li><li>通过class关键字定义一个组件 <ul><li>constructor是可选的，通常需要在constructor中初始化一些数据</li><li>this.state中维护的数据就是组件内部的数据</li><li><strong>render方法是class组件中唯一必须实现的方法</strong></li></ul></li></ul><h4 id="render函数" tabindex="-1">render函数 <a class="header-anchor" href="#render函数" aria-label="Permalink to &quot;render函数&quot;">​</a></h4><ul><li>render函数在组件第一次渲染时被调用</li><li>当<code>this.props</code>或<code>this.state</code>发生变化时被调用</li></ul><p>被调用时组件内会检查<code>this.props</code>和<code>this.state</code>是否发生变化，并且返回下面的返回值之一：</p><ul><li>React元素 <ul><li>通常通过JSX创建</li><li>例如<code>&lt;div /&gt;</code>会被React渲染为DOM节点，而<code>&lt;SomeComponent /&gt;</code>会被React渲染为自定义组件</li><li>无论是<code>&lt;div /&gt;</code>还是<code>&lt;SomeComponent /&gt;</code>，他们都为React元素</li></ul></li><li>数组或Fragments组件 <ul><li>允许通过render方法同时返回多个元素</li></ul></li><li>字符串或数字 <ul><li>元素会被渲染</li></ul></li><li>boolean/null/undefined类型 <ul><li>元素不会被渲染</li></ul></li></ul><h3 id="函数组件" tabindex="-1">函数组件 <a class="header-anchor" href="#函数组件" aria-label="Permalink to &quot;函数组件&quot;">​</a></h3><p>函数组件不需要继承自任何父类，函数的返回值相当于render函数的返回值，表示组件要渲染的内容</p><p>修改前文中编写的<code>App.jsx</code>即可：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">App</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hello, React!</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><ul><li>函数组件是使用function定义的函数，函数的返回值会返回与render函数相同的内容，表示组件要渲染的内容</li><li>函数组件有自己的特点（在无hooks的情况下，引入hooks后函数组件与类组件一样强大） <ul><li>没有生命周期，也会被更新并挂在，但是没有生命周期函数</li><li>this关键字不能指向组件实例，因为没有组件实例</li><li>没有内部状态（state）</li></ul></li></ul><h2 id="组件的生命周期" tabindex="-1">组件的生命周期 <a class="header-anchor" href="#组件的生命周期" aria-label="Permalink to &quot;组件的生命周期&quot;">​</a></h2><p>我们需要在组件的不同生命周期中执行不同的操作，比如添加解除监听器、发起网络请求等</p><p><img src="/assets/react-life-cycle.67e890c0.png" alt="React Life Cycle: https://projects.wojtekmaj.pl/react-lifecycle-methods-diagram/"></p><p>结合上图，解读一下组件的完整生命周期：</p><ul><li>组件挂载后 调用构造方法 constructor</li><li>执行 render 方法</li><li>组件挂载完毕 <code>componentDidMount</code></li><li>后续，当props发生修改 或调用了setState触发state改变 或调用forceUpdate触发组件更新 <ul><li>重新执行render函数 根据修改后的最新状态更新视图</li><li>React帮我们更新DOM和refs</li><li>更新回调 <code>componentDidUpdate</code> 被调用</li></ul></li><li>组件卸载 一般是条件渲染切换路由时发生卸载</li><li>组件被卸载前 <code>componentWillUnmount</code> 被调用 <ul><li>可以用来执行一些清理副作用的操作</li><li>如解除监听器等</li></ul></li></ul><p>总结一下常用的生命周期钩子：</p><ul><li><code>componentDidMount</code> 组件挂载后</li><li><code>componentDidUpdate</code> 组件更新后</li><li><code>componentWillUnmount</code> 组件卸载前</li></ul><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// LifeCycle.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">LifeCycle</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">addCount</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">+</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">componentDidMount</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">LifeCycle componentDidMount</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">componentDidUpdate</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">LifeCycle componentDidUpdate</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">componentWillUnmount</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">LifeCycle componentWillUnmount</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">LifeCycle render</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">LifeCycle</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">p</span><span style="color:#89DDFF;">&gt;{this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">p</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">+</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br></div></div><h3 id="constructor" tabindex="-1">constructor <a class="header-anchor" href="#constructor" aria-label="Permalink to &quot;constructor&quot;">​</a></h3><p>一般来讲 constructor 中只完成两件事情</p><ul><li>给this.state赋初值 初始化组件内部状态</li><li>为事件处理函数绑定实例(.bind(this))</li></ul><p>如果不初始化state或不进行方法绑定，则不需要为React组件实现构造函数</p><h3 id="componentdidmount" tabindex="-1">componentDidMount <a class="header-anchor" href="#componentdidmount" aria-label="Permalink to &quot;componentDidMount&quot;">​</a></h3><p>该生命周期钩子会在组件挂载后被立即调用，相当于Vue中的onMounted</p><p>在该生命周期钩子中可以获取到组件的DOM结构，通常在其中完成以下操作：</p><ul><li>依赖于DOM的操作 需要操作DOM</li><li>在此处发送网络请求 (Official Recommend)</li><li>在此处添加一些订阅监听回调 (在 componentWillUnmount 中取消订阅)</li></ul><h3 id="componentdidupdate" tabindex="-1">componentDidUpdate <a class="header-anchor" href="#componentdidupdate" aria-label="Permalink to &quot;componentDidUpdate&quot;">​</a></h3><p>会在组件更新后被立即调用，首次渲染不会执行此方法</p><ul><li>每次组件发生更新后，可以在此回调中对DOM进行操作</li><li>如果对更新前后的props进行了比较，也可以选择在此处进行网络请求 <ul><li>比如当props未发生改变，则不执行网络请求</li></ul></li></ul><h3 id="componentwillunmount" tabindex="-1">componentWillUnmount <a class="header-anchor" href="#componentwillunmount" aria-label="Permalink to &quot;componentWillUnmount&quot;">​</a></h3><p>组件卸载及销毁之前调用</p><ul><li>在此回调中执行必要的清理操作</li><li>例如 清除timer 取消网络请求 或取消在 componentDidMount 中创建的订阅等</li></ul><h3 id="不常用的生命周期" tabindex="-1">不常用的生命周期 <a class="header-anchor" href="#不常用的生命周期" aria-label="Permalink to &quot;不常用的生命周期&quot;">​</a></h3><ul><li>static getDeivedStateFromProps <ul><li>state的值在任何时候都依赖props时使用，该方法返回一个对象来更新state</li></ul></li><li>shouldComponentUpdate <ul><li>对外部条件进行显式比较 决定是否需要对组件进行更新</li><li>在此生命周期回调中返回false时 不会触发re-render 可以完成一些性能优化</li></ul></li><li>getSnapshotBeforeUpdate <ul><li>在更新前获取快照 用于更新DOM前对部分数据进行保存</li><li>比如在DOM更新前获取并保存当前滚动位置</li></ul></li></ul><h2 id="组件间通信" tabindex="-1">组件间通信 <a class="header-anchor" href="#组件间通信" aria-label="Permalink to &quot;组件间通信&quot;">​</a></h2><p>组件间通过props通信</p><ul><li>父组件通过直接在子组件上添加属性 <code>title={someValue}</code> 传递数据</li><li>子组件中通过 props 参数获取父组件传递来的数据</li></ul><p>需要注意的是，子组件中需要通过 <code>super(props)</code> 将props注册给父类，这样才能通过<code>this.props</code>获取到props</p><p>但是默认情况下React帮我们完成了这个操作，我们也就不必手动在constructor写了</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Header.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Header</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// constructor(props) {</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// super(props)</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// }</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Title: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">tab</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">index</span><span style="color:#89DDFF;">}&gt;{</span><span style="color:#A6ACCD;">tab</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Header </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Header</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Header</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">title</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Custom Title</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">count</span><span style="color:#89DDFF;">={</span><span style="color:#F78C6C;">1</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">tabs</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">[</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Category</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">User</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br></div></div><p>上文中的例子我们从父组件向子组件传递数据，但是数据都为静态的</p><p>我们再完成一个动态数据的绑定，用到了axios请求网络数据，并将数据动态传递给子组件</p><p>在父组件的 componentDidMount 中发起网络请求，获取到 postList 后通过props动态传递给子组件 Content 展示出来</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Content.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Content</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">postList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">postList</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">post</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">post</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">id</span><span style="color:#89DDFF;">}&gt;{</span><span style="color:#A6ACCD;">post</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> axios </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">axios</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Content </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Content</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> postList</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> []</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">componentDidMount</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">axios</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">get</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">https://jsonplaceholder.typicode.com/posts</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">)</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">then</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">res</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">setState</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> postList</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">res</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">data</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">postList</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Content</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">postList</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">postList</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br></div></div><h3 id="子组件向父组件通信" tabindex="-1">子组件向父组件通信 <a class="header-anchor" href="#子组件向父组件通信" aria-label="Permalink to &quot;子组件向父组件通信&quot;">​</a></h3><p>除了父组件向下传递数据，子组件也需要向上传递数据给父组件。</p><p>在React中是通过父组件提供给子组件一个回调函数，在子组件中调用回调函数，从而达到子组件向父组件通信的目的</p><p>父组件在提供数据状态 <code>count</code> 的同时，也提供了增减 <code>count</code> 的回调函数 <code>addCount</code> 和 <code>subCount</code>，子组件通过调用回调即可修改状态值</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Counter.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Counter</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">subCount</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">subCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">-</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">+</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Counter </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Counter</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">addCount</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">+</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">subCount</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> count</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">-</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">1</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Counter</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">count</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">addCount</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">addCount</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">subCount</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">subCount</span><span style="color:#89DDFF;">}&gt;&lt;/</span><span style="color:#FFCB6B;">Counter</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br></div></div><h3 id="参数proptypes" tabindex="-1">参数propTypes <a class="header-anchor" href="#参数proptypes" aria-label="Permalink to &quot;参数propTypes&quot;">​</a></h3><p>我们可以对props传递值的类型做限制 （目前官方已不再推荐使用prop-types 建议直接上TypeScript）</p><ul><li>如果项目中默认集成了Flow或TypeScript，可以直接进行类型验证</li><li>如果没有集成，则可以通过 prop-types 库来进行参数类型验证</li><li>从React v15.5起，React.PropTypes独立成为了一个npm包 prop-types 库</li></ul><div class="language-sh line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">sh</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#FFCB6B;">pnpm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">add</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">prop-types</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><p>以之前的类组件 Header 为例，为其添加类型限制：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Header.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line highlighted"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> PropTypes </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">prop-types</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Header</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// constructor(props) {</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// super(props)</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// }</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Title: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">title</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">count</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">tab</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">key</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">index</span><span style="color:#89DDFF;">}&gt;{</span><span style="color:#A6ACCD;">tab</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">li</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">ul</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line highlighted"><span style="color:#A6ACCD;">Header</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">propTypes </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">title</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> PropTypes</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">string</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isRequired</span><span style="color:#89DDFF;">,</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> PropTypes</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">number</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isRequired</span><span style="color:#89DDFF;">,</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">tabs</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> PropTypes</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">array</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">isRequired</span></span>
<span class="line highlighted"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">Header</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">defaultProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">title</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Default Title</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br></div></div><ul><li>可以直接在组件类上添加<code>.propsType</code>为其添加类型检查</li><li>也可以添加<code>.defaultProps</code>为其传入默认值</li></ul><p>需要注意的是，这里的类型限制和Vue做的defineProps类型限制是类似的，如果没有IDE Extension做额外检查，其类型检查都是在运行时进行的</p><p>如果props类型发生不匹配，在运行时会在控制台抛出错误，而编译是可以正常完成的</p><blockquote><p>Warning: Failed prop type: Invalid prop <code>title</code> of type <code>number</code> supplied to <code>Header</code>, expected <code>string</code>.</p></blockquote><p>相比之下，TypeScript可以完成静态的类型检查，帮助我们更早的发现错误</p><h3 id="组件通信案例-tab栏切换" tabindex="-1">组件通信案例 Tab栏切换 <a class="header-anchor" href="#组件通信案例-tab栏切换" aria-label="Permalink to &quot;组件通信案例 Tab栏切换&quot;">​</a></h3><p>展示一个Tabs，点击切换页面，并切换不同的Tab激活状态。</p><p>切换activeIndex后，触发Tabs组件和下方Pages组件的重新渲染</p><p>这里对className的拼接可以用第三方库 classnames 替换</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Tabs.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Tabs</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">changeTab</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">tabs</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">display</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">flex</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">tabName</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">[</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">tab</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">tab-active</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">join</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#82AAFF;">changeTab</span><span style="color:#A6ACCD;">(index)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">margin</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">5</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">cursor</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">pointer</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">transition</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">all 0.2s</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">color</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">black</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">borderBottom</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">2px solid red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabName</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Tabs </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Tabs</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> tabs</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hot</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Category</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Profile</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeTab</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">index</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Tabs</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">tabs</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">activeIndex</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">changeTab</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeTab</span><span style="color:#89DDFF;">}&gt;&lt;/</span><span style="color:#FFCB6B;">Tabs</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Home</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hot</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hot</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Category</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Category</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Profile</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Profile</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br></div></div><h2 id="react中的插槽" tabindex="-1">React中的插槽 <a class="header-anchor" href="#react中的插槽" aria-label="Permalink to &quot;React中的插槽&quot;">​</a></h2><p>React并不存在插槽的概念，但是可以通过<code>props.children</code>来实现类似的效果</p><ul><li>可以通过向子组件传递<code>props.children</code>子元素来决定子组件内渲染何种内容的标签</li><li>我们在子组件标签内书写的内容都会默认作为<code>props.children</code>传递给子组件</li></ul><h3 id="通过children实现插槽" tabindex="-1">通过children实现插槽 <a class="header-anchor" href="#通过children实现插槽" aria-label="Permalink to &quot;通过children实现插槽&quot;">​</a></h3><p>实现一个导航栏NavBar组件，左中右布局，渲染内容由父组件决定</p><p>需要注意的是 如果只传入了一个子标签，那么<code>props.children</code>不再是一个数组，需要对此做额外判断</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// NavBar.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">NavBar</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">children</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Array</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">isArray</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">children</span><span style="color:#F07178;">) </span><span style="color:#89DDFF;">||</span><span style="color:#F07178;"> (</span><span style="color:#A6ACCD;">children</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> [</span><span style="color:#A6ACCD;">children</span><span style="color:#F07178;">])</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">nav-bar</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">display</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">flex</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">justifyContent</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">space-between</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">alignContent</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">center</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">left</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">children[</span><span style="color:#F78C6C;">0</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">center</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">children[</span><span style="color:#F78C6C;">1</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">right</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">children[</span><span style="color:#F78C6C;">2</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> NavBar </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/NavBar</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">NavBar</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Back</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Search</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Menu</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#FFCB6B;">NavBar</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br></div></div><h3 id="通过props实现插槽" tabindex="-1">通过props实现插槽 <a class="header-anchor" href="#通过props实现插槽" aria-label="Permalink to &quot;通过props实现插槽&quot;">​</a></h3><p>相比于通过<code>props.children</code>传递插槽，通过props实现的插槽更具确定性</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// NavBar.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">NavBar</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">left</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">center</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">right</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">nav-bar</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">display</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">flex</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">justifyContent</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">space-between</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">alignContent</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">center</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">left</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">left</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">center</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">center</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">right</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">right</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> NavBar </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/NavBar</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">left</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Back</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">span</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">center</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Search</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">right</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Menu</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">NavBar</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">left</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">left</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">center</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">center</span><span style="color:#89DDFF;">} </span><span style="color:#C792EA;">right</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">right</span><span style="color:#89DDFF;">}&gt;&lt;/</span><span style="color:#FFCB6B;">NavBar</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br></div></div><h3 id="作用域插槽" tabindex="-1">作用域插槽 <a class="header-anchor" href="#作用域插槽" aria-label="Permalink to &quot;作用域插槽&quot;">​</a></h3><p>在Vue中，可以通过作用域插槽，在父组件插槽内容中注入插槽的数据</p><ul><li>标签与结构由父组件决定</li><li>数据内容由子组件对外暴露</li></ul><p>重写之前的Tabs例子，可以将插槽传递的内容由静态的React元素变为一个函数，这样在子组件内部就可以通过函数传参，动态地对外暴露数据</p><p>之前每个Tab使用<code>span</code>标签书写的，通过作用域插槽，我们将它通过<code>button</code>标签渲染出来</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// Tabs.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Tabs</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">changeTab</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabSlot</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">props</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">=</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">tabs</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">display</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">flex</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">tabName</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">className</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">[</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">tab</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">tab-active</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#A6ACCD;">]</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">join</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;&#39;</span><span style="color:#A6ACCD;">)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={</span><span style="color:#82AAFF;">changeTab</span><span style="color:#A6ACCD;">(index)</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">style</span><span style="color:#89DDFF;">={{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">margin</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">5</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">cursor</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">pointer</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">transition</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">all 0.2s</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">color</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">black</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">borderBottom</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> activeIndex </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> index </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">2px solid red</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;&#39;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">}}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabSlot </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">tabSlot</span><span style="color:#A6ACCD;">(tabName) </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> tabName</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> ))</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Tabs </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Tabs</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> tabs</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> [</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hot</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Category</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Profile</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#F78C6C;">0</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeTab</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">index</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> activeIndex</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">index</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Tabs</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">tabs</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">tabs</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">activeIndex</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">activeIndex</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">changeTab</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeTab</span><span style="color:#89DDFF;">}</span></span>
<span class="line highlighted"><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">tabSlot</span><span style="color:#89DDFF;">={(</span><span style="color:#A6ACCD;font-style:italic;">content</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;{</span><span style="color:#A6ACCD;">content</span><span style="color:#89DDFF;">}&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#89DDFF;"> &gt;&lt;/</span><span style="color:#FFCB6B;">Tabs</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Home</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Home</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Hot</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Hot</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Category</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Category</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">tabs[activeIndex] </span><span style="color:#89DDFF;">===</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">Profile</span><span style="color:#89DDFF;">&#39;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;&amp;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Profile</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br><span class="line-number">62</span><br><span class="line-number">63</span><br><span class="line-number">64</span><br><span class="line-number">65</span><br><span class="line-number">66</span><br></div></div><h2 id="context跨组件传参" tabindex="-1">Context跨组件传参 <a class="header-anchor" href="#context跨组件传参" aria-label="Permalink to &quot;Context跨组件传参&quot;">​</a></h2><p>非父子组件之间的数据共享</p><ul><li>props层层传递 跨组件会很不方便 对于中间那些本不需要这些props数据的组件是冗余的</li><li>第三方状态库 外置于React 如Redux （实际开发中较为常用）</li><li>事件总线 ...</li></ul><p>针对跨组件传参的场景，React提供了一个API名为Context</p><ul><li>Context 提供了一个在组件之间共享此类值的方式，而不是显式地通过组件树逐层传递props</li><li>使用 Context 共享那些全局的数据，如主题色、用户登录状态、locales等</li></ul><h3 id="用context实现跨组件传参" tabindex="-1">用Context实现跨组件传参 <a class="header-anchor" href="#用context实现跨组件传参" aria-label="Permalink to &quot;用Context实现跨组件传参&quot;">​</a></h3><p>假设有App Profile UserCard三个嵌套组件，我们希望App中的 <code>isDarkMode</code> 状态能够透传到UserCard组件中</p><ul><li>全局通过 <code>createContext</code> 创建一个上下文</li><li>根组件通过 <code>DarkModeContext.Provider</code> 标签与 <code>value</code> 传递值到上下文中</li><li>需要使用到该值的子组件通过 <code>UserCard.contextType = DarkModeContext</code> 绑定到上下文</li><li>随后即可在子组件中通过 <code>this.context</code> 获取到此上下文当前绑定的状态值</li></ul><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// context.js</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">createContext</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> DarkModeContext </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createContext</span><span style="color:#A6ACCD;">()</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> Profile </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./components/Profile</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">DarkModeContext</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./context</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">App</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#F07178;">()</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> darkMode</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#FF9CAC;">false</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">changeDarkMode</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#F07178;">setState(</span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> darkMode</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">!this.</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">darkMode</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">darkMode</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">DarkModeContext.Provider</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">value</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">darkMode</span><span style="color:#89DDFF;">}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Profile</span><span style="color:#89DDFF;"> /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeDarkMode</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change DarkMode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#FFCB6B;">DarkModeContext.Provider</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// Profile.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> UserCard </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">./UserCard</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Profile</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">UserCard</span><span style="color:#89DDFF;"> /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// UserCard.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> React</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">Component</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">react</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">DarkModeContext</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">../context</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">class</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">UserCard</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">extends</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Component</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">render</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">UserCard</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{this.</span><span style="color:#A6ACCD;">context </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Dark Mode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Light Mode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">UserCard</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">contextType </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> DarkModeContext</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br><span class="line-number">62</span><br><span class="line-number">63</span><br><span class="line-number">64</span><br></div></div><p>在类组件中可以通过Context共享数据，而函数组件中的this并没有指向组件实例，那么在函数式组件中应当如何使用？</p><p>用函数式组件重写一下 UserCard</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// UserCard.jsx</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">DarkModeContext</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">from</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">../context</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">default</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">UserCard</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">DarkModeContext.Consumer</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{(</span><span style="color:#A6ACCD;font-style:italic;">context</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> (</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">UserCard</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h1</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">context </span><span style="color:#89DDFF;">?</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Dark Mode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Light Mode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">h2</span><span style="color:#89DDFF;">&gt;}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> )</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#FFCB6B;">DarkModeContext.Consumer</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><p>如果同时需要共享多个状态，Provider可以嵌套，那么在子组件中可以通过不同的Context.Consumer获取到不同的全局上下文，执行不同的操作，展示不同的内容</p><h3 id="react-createcontext" tabindex="-1">React.createContext <a class="header-anchor" href="#react-createcontext" aria-label="Permalink to &quot;React.createContext&quot;">​</a></h3><ul><li>创建一个需要共享的Context对象</li><li>如果一个组件订阅了Context，那么这个组件会从自身最近的那个匹配的Provider中读取到当前的context值</li><li>defaultValue是组件在顶层查找过程中没有找到对应的Provider，那么就使用默认值</li><li><code>const SomeContext = React.createContext(defaultValue)</code></li></ul><h3 id="context-provider" tabindex="-1">Context.Provider <a class="header-anchor" href="#context-provider" aria-label="Permalink to &quot;Context.Provider&quot;">​</a></h3><ul><li>每个Context对象都会返回一个Provider组件，它允许消费组件订阅Context的变化</li><li>Provider接收一个value属性，用于将变化的值传递给消费组件Consumer</li><li>一个Provider可以与多个Consumer创建关系</li><li>多个Provider可以嵌套使用，内层数据会覆盖外层数据</li><li>当Provider的value发生变化时，其内部的所有Consumer组件都会重新渲染</li></ul><h3 id="class-contexttype" tabindex="-1">Class.contextType <a class="header-anchor" href="#class-contexttype" aria-label="Permalink to &quot;Class.contextType&quot;">​</a></h3><ul><li>挂载在类组件上的 <code>contextType</code> 属性会被重新赋值为一个由 <code>React.createContext</code> 创建的Context对象</li><li>这允许你在类组件中通过 <code>this.context</code> 获取到<strong>最近的Context</strong>的值</li><li>任何生命周期都能访问到这个值</li></ul><h3 id="context-consumer" tabindex="-1">Context.Consumer <a class="header-anchor" href="#context-consumer" aria-label="Permalink to &quot;Context.Consumer&quot;">​</a></h3><ul><li>帮你在<strong>函数式组件</strong>中完成订阅context （函数式组件中没有this）</li><li>当Consumer订阅到context变更，会触发其内部传递的函数</li><li>传入Consumer的函数接收当前的context值，返回一个React元素节点</li></ul><h3 id="关于defaultvalue" tabindex="-1">关于defaultValue <a class="header-anchor" href="#关于defaultvalue" aria-label="Permalink to &quot;关于defaultValue&quot;">​</a></h3><p>什么时候会用到创建Context时传入的defaultValue？</p><p>如果子组件通过 <code>this.context</code> 向上查找时没有找到相应的Provider，则使用Context的默认值</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">darkMode</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">DarkModeContext.Provider</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">value</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">darkMode</span><span style="color:#89DDFF;">}&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">onClick</span><span style="color:#89DDFF;">={this.</span><span style="color:#A6ACCD;">changeDarkMode</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Change DarkMode</span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#FFCB6B;">DarkModeContext.Provider</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Profile</span><span style="color:#89DDFF;"> /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h3 id="props属性展开" tabindex="-1">props属性展开 <a class="header-anchor" href="#props属性展开" aria-label="Permalink to &quot;props属性展开&quot;">​</a></h3><p>如果我们希望将一个对象中的所有属性都作为props传递给子组件，可以在子组件标签上直接展开该对象</p><p>类似于Vue中的<code>v-bind=&quot;childProps&quot;</code>，一次绑定所有属性到子组件</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight has-highlighted-lines"><code><span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">render</span><span style="color:#A6ACCD;">() </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">childProps</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">state</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> (</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Child</span><span style="color:#89DDFF;"> {...</span><span style="color:#A6ACCD;">childProps</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">div</span><span style="color:#89DDFF;">&gt;</span></span>
<span class="line"><span style="color:#F07178;"> )</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><p>如果你确实希望层层传递props来实现跨组件通信，那么可以在render函数中直接将<code>this.props</code>进行属性展开，虽然不推荐这样的做法：</p><div class="language-tsx line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">tsx</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">App</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// Profile.jsx</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Profile</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// UserCard.jsx</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">UserCard</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// Details.jsx</span></span>
<span class="line"><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Details</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} /&gt;</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div></div></div></main><footer class="VPDocFooter" data-v-25140dfd data-v-b9eb50cb><!--[--><!--]--><div class="edit-info" data-v-b9eb50cb><div class="edit-link" data-v-b9eb50cb><a class="VPLink link edit-link-button" href="https://github.com/ZiuChen/ZiuChen.github.io/edit/main/docs/note/React.md" target="_blank" rel="noreferrer" data-v-b9eb50cb data-v-fd6e3585><!--[--><svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 24 24" class="edit-link-icon" aria-label="edit icon" data-v-b9eb50cb><path d="M18,23H4c-1.7,0-3-1.3-3-3V6c0-1.7,1.3-3,3-3h7c0.6,0,1,0.4,1,1s-0.4,1-1,1H4C3.4,5,3,5.4,3,6v14c0,0.6,0.4,1,1,1h14c0.6,0,1-0.4,1-1v-7c0-0.6,0.4-1,1-1s1,0.4,1,1v7C21,21.7,19.7,23,18,23z"></path><path d="M8,17c-0.3,0-0.5-0.1-0.7-0.3C7,16.5,6.9,16.1,7,15.8l1-4c0-0.2,0.1-0.3,0.3-0.5l9.5-9.5c1.2-1.2,3.2-1.2,4.4,0c1.2,1.2,1.2,3.2,0,4.4l-9.5,9.5c-0.1,0.1-0.3,0.2-0.5,0.3l-4,1C8.2,17,8.1,17,8,17zM9.9,12.5l-0.5,2.1l2.1-0.5l9.3-9.3c0.4-0.4,0.4-1.1,0-1.6c-0.4-0.4-1.2-0.4-1.6,0l0,0L9.9,12.5z M18.5,2.5L18.5,2.5L18.5,2.5z"></path></svg> Edit this page on GitHub<!--]--><!----></a></div><div class="last-updated" data-v-b9eb50cb><p class="VPLastUpdated" data-v-b9eb50cb data-v-f683efee>Updated Date: <time datetime="2023-04-17T08:27:23.000Z" data-v-f683efee></time></p></div></div><div class="prev-next" data-v-b9eb50cb><div class="pager" data-v-b9eb50cb><!----></div><div class="pager" data-v-b9eb50cb><a class="pager-link next" href="/project/ClipboardManager/" data-v-b9eb50cb><span class="desc" data-v-b9eb50cb>Next page</span><span class="title" data-v-b9eb50cb>超级剪贴板</span></a></div></div></footer><!--[--><!--]--></div></div></div><!--[--><!--]--></div></div><footer class="VPFooter has-sidebar" data-v-6305e88a data-v-58542612><div class="container" data-v-58542612><p class="message" data-v-58542612>Released under the MIT License.</p><p class="copyright" data-v-58542612>Copyright © 2019-present Ziu Chen</p></div></footer><!--[--><!--]--></div></div>
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