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href="/article/%E6%B7%B1%E5%85%A5Vue3%E6%BA%90%E7%A0%81%EF%BC%8C%E7%9C%8B%E7%9C%8BVue.use%E5%90%8E%E7%A9%B6%E7%AB%9F%E5%8F%91%E7%94%9F%E4%BA%86%E4%BB%80%E4%B9%88%EF%BC%9F.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>深入Vue3源码，看看Vue.use后究竟发生了什么？</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/article/%E6%B7%B1%E5%85%A5%E7%90%86%E8%A7%A3Proxy%E4%B8%8EReflect.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>深入理解Proxy与Reflect</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></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-f16f934a><!--[--><p class="text" data-v-f16f934a>深入理解浏览器缓存机制</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></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-f16f934a><!--[--><p class="text" data-v-f16f934a>深入理解浏览器运行原理</p><!--]--></a><!----></div><!----></div><!--]--></div></section></div><div class="group" data-v-ea943bcb><section class="VPSidebarItem level-0 collapsible has-active" data-v-ea943bcb data-v-f16f934a><div class="item" role="button" tabindex="0" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><h2 class="text" data-v-f16f934a>学习笔记</h2><div class="caret" role="button" aria-label="toggle section" tabindex="0" data-v-f16f934a><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" viewbox="0 0 24 24" class="caret-icon" data-v-f16f934a><path d="M9,19c-0.3,0-0.5-0.1-0.7-0.3c-0.4-0.4-0.4-1,0-1.4l5.3-5.3L8.3,6.7c-0.4-0.4-0.4-1,0-1.4s1-0.4,1.4,0l6,6c0.4,0.4,0.4,1,0,1.4l-6,6C9.5,18.9,9.3,19,9,19z"></path></svg></div></div><div class="items" data-v-f16f934a><!--[--><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/JavaScript.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>JavaScript基础</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/CSS.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>CSS基础</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/JavaScriptEnhanced.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>JavaScript进阶</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/Front-end%20Engineering.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>前端工程化</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/SSR.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>服务端渲染</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/React.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>React基础</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/React%20Hooks.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>React Hooks</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/Redux.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>Redux</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/React%20Router.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>React Router</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-f16f934a data-v-f16f934a><div class="item" data-v-f16f934a><div class="indicator" data-v-f16f934a></div><a class="VPLink link link" href="/note/MySQL.html" data-v-f16f934a><!--[--><p class="text" data-v-f16f934a>MySQL</p><!--]--></a><!----></div><!----></div><!--]--></div></section></div><!--]--><!--[--><!--]--></nav></aside><div class="VPContent has-sidebar" id="VPContent" data-v-4b282efc data-v-3d0b81df><div class="VPDoc has-sidebar has-aside" data-v-3d0b81df data-v-f0e11dcf><!--[--><!--]--><div class="container" data-v-f0e11dcf><div class="aside" data-v-f0e11dcf><div class="aside-curtain" data-v-f0e11dcf></div><div class="aside-container" data-v-f0e11dcf><div class="aside-content" data-v-f0e11dcf><div class="VPDocAside" data-v-f0e11dcf data-v-0c849b30><!--[--><!--]--><!--[--><!--]--><div class="VPDocAsideOutline" data-v-0c849b30 data-v-ecb1c3c3><div class="content" data-v-ecb1c3c3><div class="outline-marker" data-v-ecb1c3c3></div><div class="outline-title" data-v-ecb1c3c3>On this page</div><nav aria-labelledby="doc-outline-aria-label" data-v-ecb1c3c3><span class="visually-hidden" id="doc-outline-aria-label" data-v-ecb1c3c3> Table of Contents for current page </span><ul class="root" data-v-ecb1c3c3 data-v-61596211><!--[--><!--]--></ul></nav></div></div><!--[--><!--]--><div class="spacer" data-v-0c849b30></div><!--[--><!--]--><!----><!--[--><!--]--><!--[--><!--]--></div></div></div></div><div class="content" data-v-f0e11dcf><div class="content-container" data-v-f0e11dcf><!--[--><!--]--><!----><main class="main" data-v-f0e11dcf><div style="position:relative;" class="vp-doc _note_Redux" data-v-f0e11dcf><div><h1 id="redux" tabindex="-1">Redux <a class="header-anchor" href="#redux" aria-label="Permalink to &quot;Redux&quot;">​</a></h1><h2 id="理解javascript的纯函数" tabindex="-1">理解JavaScript的纯函数 <a class="header-anchor" href="#理解javascript的纯函数" aria-label="Permalink to &quot;理解JavaScript的纯函数&quot;">​</a></h2><ul><li>函数式编程中有一个非常重要的概念 <strong>纯函数</strong>，JavaScript符合函数式编程的范式，所以也有纯函数的概念 <ul><li>在React开发中，纯函数被多次提及：</li><li>React组件被要求像一个纯函数（为什么是像，因为还有类组件）</li><li>Redux中有一个reducer的概念，同样是要求必须是一个纯函数</li></ul></li><li>掌握纯函数对于理解很多框架的设计都是有帮助的</li></ul><p>一个纯函数必然具备以下特征：</p><ul><li>确定的输入一定产生确定的输出</li><li>函数的执行过程中，不能产生副作用</li></ul><h2 id="为什么需要redux" tabindex="-1">为什么需要Redux <a class="header-anchor" href="#为什么需要redux" aria-label="Permalink to &quot;为什么需要Redux&quot;">​</a></h2><ul><li>JS需要管理的状态越来越多，越来越复杂</li><li>状态不断发生变化之间又相互依赖，这要求视图层也能同步更新</li><li>React提供了自动更新视图的方法，但状态仍需要手动管理</li><li>Redux可以帮我们管理状态，提供了<strong>可预测的状态管理</strong></li><li>框架无关，体积只有2KB大小</li></ul><h2 id="redux的核心理念" tabindex="-1">Redux的核心理念 <a class="header-anchor" href="#redux的核心理念" aria-label="Permalink to &quot;Redux的核心理念&quot;">​</a></h2><p>Redux的核心理念 Store</p><ul><li>定义一个统一的规范来操作数据，这样就可以做到对数据的跟踪</li><li><code>list.push()</code> <code>list[0].age = 18</code></li></ul><p>Redux的核心理念 Action</p><ul><li>Redux要求：要修改数据，必须通过Action来修改</li><li>所有数据的变化，必须通过派发（Patch）Action来更新</li><li>Action是一个普通的JS对象，用来描述此次更新的type与content</li><li><code>const action = { type: &#39;ADD_ITEM&#39;, item: { name: &#39;Ziu&#39;, age: 18 } }</code></li></ul><p>Redux的核心理念 Reducer</p><ul><li>如何将Store和Action联系在一起？</li><li>reducer是一个纯函数</li><li>完成的工作就是：将传入的state和action结合起来，生成一个新的state</li><li><code>patch</code> =&gt; <code>reducer</code> =&gt; <code>newState</code> =&gt; <code>Store</code></li></ul><h2 id="redux-demo" tabindex="-1">Redux Demo <a class="header-anchor" href="#redux-demo" aria-label="Permalink to &quot;Redux Demo&quot;">​</a></h2><p>下例中，通过<code>createStore</code>创建了一个Store（已经不推荐了）</p><ul><li>initialState用于在调用<code>createStore</code>时作为默认值传入<code>reducer</code></li><li>后续每次<code>store.dispatch</code>都会调用<code>reducer</code></li><li>通过<code>reducer</code>更新state中的数据</li></ul><p>在React中，可以通过<code>store.subscribe</code>注册State变化的监听回调</p><ul><li>当state发生变化时，通过调用<code>this.forceUpdate</code>触发组件的更新</li><li>一般情况下，我们在<code>componentDidMount</code>注册监听回调，在<code>componentWillUnmount</code>解除监听</li></ul><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-OoFsu" id="tab-RScH5nQ" checked="checked"><label for="tab-RScH5nQ">App.jsx</label><input type="radio" name="group-OoFsu" id="tab-oRrHYbr"><label for="tab-oRrHYbr">index.js</label></div><div class="blocks"><div class="language-tsx active 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;">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;">PureComponent</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;"> store </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;">./store</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;">PureComponent</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></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:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// Subscribe to the store</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">subscribe</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:#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;">subscribe</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#F07178;">())</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">this.</span><span style="color:#82AAFF;">forceUpdate</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;">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;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">unsubscribe</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:#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;">App</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;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</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;">p</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Name: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">INCREMENT</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;">}&gt;</span><span style="color:#A6ACCD;"> +1 </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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">DECREMENT</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;">}&gt;</span><span style="color:#A6ACCD;"> -1 </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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">CHANGE_NAME</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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:#89DDFF;">&#39;</span><span style="color:#C3E88D;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;"> CHANGE_NAME</span><span style="color:#89DDFF;">{</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;"> </span><span style="color:#89DDFF;">&#39;</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;">&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></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;">// store/index.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;">createStore</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;">redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// The initial application state</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// This is the same as the state argument we passed to the createStore function</span></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> initialState </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;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</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>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// Reducer: a pure function that takes the previous state and an action, and returns the next state.</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// (previousState, action) =&gt; newState</span></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">reducer</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> initialState</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">action</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;">reducer</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</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;">switch</span><span style="color:#F07178;"> (</span><span style="color:#A6ACCD;">action</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">type</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;">case</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">INCREMENT</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">:</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// NOTE: Keep functions pure - do not mutate the original state.</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// Desctructure the state object and return a **new object** with the updated count</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// Instead of `return state.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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</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:#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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">case</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">DECREMENT</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;font-style:italic;">return</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:#A6ACCD;">state</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:#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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">case</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">CHANGE_NAME</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;font-style:italic;">return</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:#A6ACCD;">state</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</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;font-style:italic;">default</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:#A6ACCD;">state</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;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createStore</span><span style="color:#A6ACCD;">(reducer)</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;"> store</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></div></div></div></div><p><img src="/assets/redux-usage.7df84df8.svg" alt="redux-usage"></p><h2 id="进一步封装" tabindex="-1">进一步封装 <a class="header-anchor" href="#进一步封装" aria-label="Permalink to &quot;进一步封装&quot;">​</a></h2><p>可以将耦合在一起的代码拆分到不同文件中</p><ul><li>将<code>reducer</code>抽取出来<code>reducer.js</code>，简化<code>store/index.js</code>内容</li><li>将<code>action.type</code>抽取为常量<code>constants.js</code>，使用时做导入，以保证一致性</li><li>将<code>action</code>抽取出来<code>actionFactory.js</code>，用于外部dispatch时规范类型</li></ul><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-Lc_Ah" id="tab-yo3QfIL" checked="checked"><label for="tab-yo3QfIL">index.js</label><input type="radio" name="group-Lc_Ah" id="tab-NBqMEpe"><label for="tab-NBqMEpe">constants.js</label><input type="radio" name="group-Lc_Ah" id="tab-fYcIHnY"><label for="tab-fYcIHnY">reducer.js</label><input type="radio" name="group-Lc_Ah" id="tab-xh-A3BY"><label for="tab-xh-A3BY">actionFactory.js</label></div><div class="blocks"><div class="language-tsx active 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;">// store/index.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;">createStore</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;">redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> reducer </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;">./reducer</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;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createStore</span><span style="color:#A6ACCD;">(reducer)</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;"> store</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><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;">// constants.js</span></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;"> INCREMENT </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">INCREMENT</span><span style="color:#89DDFF;">&#39;</span></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;"> DECREMENT </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">DECREMENT</span><span style="color:#89DDFF;">&#39;</span></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;"> CHANGE_NAME </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">CHANGE_NAME</span><span style="color:#89DDFF;">&#39;</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><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;">// reducer.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:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">as</span><span style="color:#A6ACCD;"> actionType </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;">./constants</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;"> initialState </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;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</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>
<span class="line"><span style="color:#89DDFF;">}</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;">reducer</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> initialState</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">action</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;">switch</span><span style="color:#F07178;"> (</span><span style="color:#A6ACCD;">action</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">type</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;">case</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">INCREMENT</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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</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:#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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">case</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">DECREMENT</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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</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:#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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">case</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">CHANGE_NAME</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>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> name</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</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;font-style:italic;">default</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:#A6ACCD;">state</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></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;">// actionFactory.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:#A6ACCD;"> </span><span style="color:#89DDFF;font-style:italic;">as</span><span style="color:#A6ACCD;"> actionType </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;">./constants</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;"> increment </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:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">INCREMENT</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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;"> decrement </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:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">DECREMENT</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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;"> changeName </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">name</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:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">CHANGE_NAME</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> name</span></span>
<span class="line"><span style="color:#89DDFF;">}</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></div></div></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;">// 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;">PureComponent</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;"> store </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;">./store</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;">increment</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">decrement</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">changeName</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;">./store/actionFactory</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;">PureComponent</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></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;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">subscribe</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:#89DDFF;">this.</span><span style="color:#82AAFF;">forceUpdate</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;">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;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">unsubscribe</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;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">App</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;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</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;">p</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Name: </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#82AAFF;">increment</span><span style="color:#A6ACCD;">())</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;"> +1 </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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#82AAFF;">decrement</span><span style="color:#A6ACCD;">())</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;"> -1 </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;">={()</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#A6ACCD;"> store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#82AAFF;">changeName</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:#A6ACCD;">))</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">CHANGE_NAME</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><h2 id="redux的三大原则" tabindex="-1">Redux的三大原则 <a class="header-anchor" href="#redux的三大原则" aria-label="Permalink to &quot;Redux的三大原则&quot;">​</a></h2><p>单一数据源</p><ul><li>整个应用程序的状态都被存储在一棵Object Tree上</li><li>且这个Object Tree只存储在一个Store中</li><li>但Redux并不强制限制创建多Store，不利于数据维护</li><li>单一数据源有利于整个应用程序的维护、追踪、修改</li></ul><p>State属性是只读的</p><ul><li>允许修改State的方法只有patch action，不要直接修改State</li><li>确保了View或网络请求都不能修改State</li><li>保证所有的修改都能被追踪、按照严格的顺序执行，不用担心竞态（race condition）的问题</li></ul><p>使用纯函数来执行修改</p><ul><li>通过reducer将旧State与新State联系在一起，并且返回一个<strong>新的State</strong></li><li>随着应用程序复杂程度增加，可以将reducer拆分为多个小的reducer，分别用于操作不同State Tree的某一部分</li><li>所有的reducer都应该是纯函数，不能产生任何的副作用</li></ul><h2 id="优化重复代码" tabindex="-1">优化重复代码 <a class="header-anchor" href="#优化重复代码" aria-label="Permalink to &quot;优化重复代码&quot;">​</a></h2><p>当编写了一些案例的时候会发现，React结合Redux时会编写很多重复的代码</p><p>在每个需要用到Redux中状态的组件中，都需要在不同生命周期做添加订阅/解除订阅的处理，组件初始化时还要从store中取最新的状态</p><p>针对重复代码的问题，可以使用之前学到的高阶组件来做优化</p><p>Redux官方提供的库<code>react-redux</code>，可以让我们更方便的在React中使用Redux</p><div class="language-bash line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">bash</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#FFCB6B;">npm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">i</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">react-redux</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><p>在Profile组件中，通过高阶函数<code>connect</code>实现的</p><p>将store中需要的状态通过<code>mapStoreToProps</code>转为props，并将需要使用store中状态的组件传入调用connect返回的函数中</p><p>在<code>Profile</code>组件中就可以从props中获取到store中的状态</p><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-vPDh8" id="tab-M07WS96" checked="checked"><label for="tab-M07WS96">App.jsx</label><input type="radio" name="group-vPDh8" id="tab-IHzAzi-"><label for="tab-IHzAzi-">Profile.jsx</label></div><div class="blocks"><div class="language-tsx active 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;">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;">PureComponent</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;">Provider</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-redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> store </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;">./store</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;">./Profile</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;">PureComponent</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:#FFCB6B;">Provider</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">store</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">store</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;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">App</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:#FFCB6B;">Profile</span><span style="color:#89DDFF;">&gt;&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;">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;">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></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><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;">// 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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">connect</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-redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// mapStateToProps is a function that</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// takes the state of the store as an argument</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// and returns an object with the data that the component needs from the store.</span></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// component will receive the data as props.</span></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapStateToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;"> </span><span style="color:#F07178;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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:#82AAFF;">connect</span><span style="color:#A6ACCD;">(mapStateToProps)(</span></span>
<span class="line"><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:#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;">p</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{this.</span><span style="color:#A6ACCD;">props</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;">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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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><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></div></div><p>我们刚刚只是完成了对State的映射，将Store中保存的全局状态state映射到了Profile组件的props中</p><p>connect还可以传入第二个参数，用于将action也映射到props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 has-highlighted-lines"><code><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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">connect</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-redux</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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">INCREMENT</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">DECREMENT</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;">./store/constants</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;"> mapStateToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;"> </span><span style="color:#F07178;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line highlighted"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapDispatchToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">dispatch</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 highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">increment</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:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> INCREMENT </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:#82AAFF;">decrement</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:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">type</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> DECREMENT </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line highlighted"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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:#82AAFF;">connect</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapStateToProps</span><span style="color:#89DDFF;">,</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> mapDispatchToProps</span></span>
<span class="line"><span style="color:#A6ACCD;">)(</span></span>
<span class="line"><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:#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;">p</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">Count: </span><span style="color:#89DDFF;">{this.</span><span style="color:#A6ACCD;">props</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 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;">props</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">increment</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;"> +1 </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#F07178;">button</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;">props</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">decrement</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;"> -1 </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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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><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>本质上是<code>connect</code>内部对操作进行了封装，把逻辑隐藏起来了：</p><ul><li>调用<code>connect</code>这个<strong>高阶函数</strong>，返回一个<strong>高阶组件</strong></li><li>为高阶组件传入映射目标组件，最后高阶组件返回一个新组件</li><li>新组件的props包含了来自Store中状态/dispatch的映射</li></ul><h2 id="异步action" tabindex="-1">异步Action <a class="header-anchor" href="#异步action" aria-label="Permalink to &quot;异步Action&quot;">​</a></h2><p>有些场景下，我们希望组件能够直接调用Store中的action来触发网络请求，并且获取到数据</p><p>但是dispatch只允许派发对象类型的Action，不能通过dispatch派发函数</p><p>可以通过中间件<code>redux-thunk</code>来对Redux做增强，让dispatch能够对函数进行派发</p><div class="language-bash line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">bash</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#FFCB6B;">npm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">i</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">redux-thunk</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><p>通过<code>applyMiddleware</code>引入<code>redux-thunk</code>这个中间件：</p><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-euaoN" id="tab-5oeokKh" checked="checked"><label for="tab-5oeokKh">index.js</label><input type="radio" name="group-euaoN" id="tab-icSIt9K"><label for="tab-icSIt9K">actionFactory.js</label><input type="radio" name="group-euaoN" id="tab-ML9-CC1"><label for="tab-ML9-CC1">list.jsx</label></div><div class="blocks"><div class="language-tsx active 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;">// store/index.js</span></span>
<span class="line highlighted"><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;">createStore</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">applyMiddleware</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;">redux</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;"> thunk </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;">redux-thunk</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> reducer </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;">./reducer</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line highlighted"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createStore</span><span style="color:#A6ACCD;">(reducer</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">applyMiddleware</span><span style="color:#A6ACCD;">(thunk))</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;"> store</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></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;">// actionFactory.js</span></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;"> fetchPostList </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;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">dispatch</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">getState</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:#82AAFF;">fetch</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>
<span class="line"><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:#A6ACCD;">res</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">json</span><span style="color:#F07178;">())</span></span>
<span class="line"><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:#82AAFF;">dispatch</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> type</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">actionType</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">FETCH_POST_LIST</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#F07178;"> list</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">res</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 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></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;">// list.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;">connect</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-redux</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;">fetchPostList</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;">./store/actionFactory</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;"> mapStateToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;"> </span><span style="color:#F07178;">list</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">list</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapDispatchToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">dispatch</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:#A6ACCD;"> </span><span style="color:#82AAFF;">fetchList</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:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#82AAFF;">fetchPostList</span><span style="color:#A6ACCD;">())</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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:#82AAFF;">connect</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapStateToProps</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapDispatchToProps</span></span>
<span class="line"><span style="color:#A6ACCD;">)(</span></span>
<span class="line"><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:#F07178;">h2</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">List</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;">={()</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:#A6ACCD;">props</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">fetchList</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Fetch List</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;">{this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">list</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">length </span><span style="color:#89DDFF;">&amp;&amp;</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;">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;">props</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">list</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;">.</span><span style="color:#A6ACCD;">id</span><span style="color:#89DDFF;">}&gt;{</span><span style="color:#A6ACCD;">item</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:#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;">}</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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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><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></div></div></div></div><ul><li>这样就可以将网络请求的具体逻辑代码隐藏到Redux中</li><li>将网络请求归于状态管理的一部分</li><li>而不是书写在组件内，不利于维护，耦合度太高</li></ul><p><code>redux-thunk</code>是如何做到可以让我们发送异步请求的？</p><ul><li>默认情况下<code>dispatch(action)</code>的action必须为一个JS对象</li><li><code>redux-thunk</code>允许我们传入一个函数作为<code>action</code></li><li>函数会被调用，并且将<code>dispatch</code>函数和<code>getState</code>函数作为入参传递给这个函数action <ul><li><code>dispatch</code> 允许我们在这之后再次派发<code>action</code></li><li><code>getState</code> 允许我们之后的一些操作依赖原来的状态，可以获取到之前的状态</li></ul></li></ul><p>下图展示了从组件调用方法，触发patch到Redux接收patch、发送网络请求、更新state的全过程：</p><p><img src="/assets/redux-async-action.0dc40e11.svg" alt="redux-async-action"></p><h2 id="拆分store" tabindex="-1">拆分Store <a class="header-anchor" href="#拆分store" aria-label="Permalink to &quot;拆分Store&quot;">​</a></h2><p>拆分Store带来的益处很多，便于多人协作、不同业务逻辑解耦等</p><p>在Redux中，拆分Store的本质是拆分不同的<code>reducer</code>函数，之前在使用<code>createStore</code>时，传入的就是<code>reducer</code>函数</p><p>之前的Store写法与用法：</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 has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// store/index.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;">createStore</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;">redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> reducer </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;">./reducer</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;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createStore</span><span style="color:#A6ACCD;">(reducer)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">list</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><p>拆分Store后的写法与用法：</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 has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// store/index.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;">createStore</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">combineReducers</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;">redux</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> counterReducer </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;">./counter</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> postListReducer </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;">./postList</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;"> reducer </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">combineReducers</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;">counter</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> counterReducer</span><span style="color:#89DDFF;">,</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">postList</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> postListReducer</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createStore</span><span style="color:#A6ACCD;">(reducer)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// App.jsx</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">counter</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">postList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</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>拆分为多个Reducer之后，需要首先<code>getState()</code>获取到整个状态树，随后指定获取到不同的模块中的状态</p><p>拆分后，不同模块下的文件是保持一致的：</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;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">store/</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># Store根目录</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">index.js</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># 导出 store 位置</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">counter/</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># Counter模块</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">actionFactory.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">constants.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">index.js</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># 统一导出</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">reducer.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">postList/</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;"># PostList模块</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">actionFactory.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">constants.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">index.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">reducer.js</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">-</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">...</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></div></div><h3 id="combinereducer函数" tabindex="-1">combineReducer函数 <a class="header-anchor" href="#combinereducer函数" aria-label="Permalink to &quot;combineReducer函数&quot;">​</a></h3><p>前面拆分Store时用到了<code>combineReducer</code>函数，将多个模块reducer组合到一起，函数内部是如何处理的？</p><ul><li>将传入的reducers合并到一个对象中，最终返回一个<code>combination</code>函数（相当于未拆分时传给<code>createStore</code>的<code>reducer</code>函数）</li><li>在执行<code>combination</code>函数的过程中，它会通过判断前后返回的数据是否相同来决定返回之前的state还是新的state</li><li>新state会触发订阅者发生对应更新，而旧state可以有效地组织订阅者发生刷新</li></ul><p>下面简单写了一下<code>combineReducer</code>的实现原理</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:#676E95;font-style:italic;">// 使用</span></span>
<span class="line"><span style="color:#82AAFF;">combineReducer</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">counter</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> combineReducer</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">postList</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> postListReducer</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#676E95;font-style:italic;">// 创建一个新的reducer</span></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">reducer</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;font-style:italic;">action</span><span style="color:#89DDFF;">)</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;">// 返回一个对象 是Store的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:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> counter</span><span style="color:#89DDFF;">:</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">counterReducer</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">counter</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</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:#82AAFF;">postListReducer</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">postList</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</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></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><h2 id="reduxtoolkit" tabindex="-1">ReduxToolkit <a class="header-anchor" href="#reduxtoolkit" aria-label="Permalink to &quot;ReduxToolkit&quot;">​</a></h2><ul><li>ReduxToolkit重构</li><li>ReduxToolkit异步</li><li>connect高阶组件</li><li>中间件的实现原理</li><li>React状态管理选择</li></ul><h2 id="认识reduxtoolkit" tabindex="-1">认识ReduxToolkit <a class="header-anchor" href="#认识reduxtoolkit" aria-label="Permalink to &quot;认识ReduxToolkit&quot;">​</a></h2><p>之前在使用<code>createStore</code>创建Store时会出现deprecated标识，推荐我们使用<code>@reduxjs/toolkit</code>包中的<code>configureStore</code>函数</p><p>Redux Toolkit是官方推荐编写Redux逻辑的方法</p><ul><li>在前面学习Redux时已经发现，Redux的逻辑编写过于繁琐、麻烦</li><li>代码分拆在不同模块中，存在大量重复代码</li><li>Redux Toolkit旨在成为编写Redux逻辑的标准方式，从而解决上面提到的问题</li><li>这个包常被称为：RTK</li></ul><h2 id="使用reduxtoolkit重写store" tabindex="-1">使用ReduxToolkit重写Store <a class="header-anchor" href="#使用reduxtoolkit重写store" aria-label="Permalink to &quot;使用ReduxToolkit重写Store&quot;">​</a></h2><p>Redux Toolkit依赖于react-redux包，所以需要同时安装这二者</p><div class="language-bash line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">bash</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#FFCB6B;">npm</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">i</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">@reduxjs/toolkit</span><span style="color:#A6ACCD;"> </span><span style="color:#C3E88D;">react-redux</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><p>Redux Toolkit的核心API主要是下述几个：</p><ul><li><code>configureStore</code> 包装createStore以提供简化的配置选项和良好的默认值 <ul><li>可以自动组合你的slice reducer 添加你提供的任何Redux中间件</li><li>默认包含redux-thunk，并启用Redux DevTools Extension</li></ul></li><li><code>createSlice</code> 创建切片 片段 <ul><li>接受reducer函数的对象、切片名称和初始状态值，并自动生成切片reducer，并带有actions</li></ul></li><li><code>createAsyncThunk</code><ul><li>接受一个动作类型字符串和一个返回Promise的函数</li><li>并生成一个<code>pending / fullfilled / rejected</code>基于该承诺分派动作类型的thunk</li></ul></li></ul><p>写一个Demo：</p><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-hnfve" id="tab-FqJHSQq" checked="checked"><label for="tab-FqJHSQq">index.js</label><input type="radio" name="group-hnfve" id="tab-zYKpx6Q"><label for="tab-zYKpx6Q">counter.js</label><input type="radio" name="group-hnfve" id="tab-P_EdTOf"><label for="tab-P_EdTOf">Counter.jsx</label></div><div class="blocks"><div class="language-tsx active 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;">// store/index.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;">configureStore</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;">@reduxjs/toolkit</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> counterSlice </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;">./features/counter</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;"> store </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">configureStore</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">reducer</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;">counter</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> counterSlice</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:#A6ACCD;">)</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;"> store</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></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;">// store/features/counter.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;">createSlice</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;">@reduxjs/toolkit</span><span style="color:#89DDFF;">&#39;</span></span>
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<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> counterSlice </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createSlice</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">counter</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;">initialState</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;">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:#A6ACCD;"> </span><span style="color:#89DDFF;">},</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">reducers</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;">addCount</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">action</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;">payload</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:#A6ACCD;">action</span></span>
<span class="line"><span style="color:#F07178;"> </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:#A6ACCD;">payload</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;">subCount</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">action</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;">payload</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:#A6ACCD;">action</span></span>
<span class="line"><span style="color:#F07178;"> </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:#A6ACCD;">payload</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:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> actions</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> reducer </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> counterSlice</span></span>
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<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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> addCount</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> subCount </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> actions</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;"> reducer</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><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 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;">connect</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-redux</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;">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:#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;">../store/features/counter</span><span style="color:#89DDFF;">&#39;</span></span>
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<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapStateToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;"> </span><span style="color:#F07178;">count</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">counter</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">count</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapDispatchToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">dispatch</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:#A6ACCD;"> </span><span style="color:#82AAFF;">increment</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">count</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:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">addCount</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">count</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:#82AAFF;">dispatch</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">action</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:#82AAFF;">decrement</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">count</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:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">subCount</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">count</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:#82AAFF;">dispatch</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">action</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 style="color:#A6ACCD;">)</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:#82AAFF;">connect</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapStateToProps</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapDispatchToProps</span></span>
<span class="line"><span style="color:#A6ACCD;">)(</span></span>
<span class="line"><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:#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;">Counter</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 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;">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:#A6ACCD;">props</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">increment</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;">+1</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;">={()</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:#A6ACCD;">props</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">decrement</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;">-1</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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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><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></div></div><p><code>createSlice</code> 函数参数解读</p><ul><li><code>name</code> 标记Slice 展示在dev-tool中</li><li><code>initialState</code> 初始化状态</li><li><code>reducers</code> 对象 对应之前的reducer函数</li><li>返回值: 一个对象 包含所有actions</li></ul><p><code>configureStore</code> 解读</p><ul><li><code>reducer</code> 将slice中的reducer组成一个对象，传入此参数</li><li><code>middleware</code> 额外的中间件 <ul><li>RTK已经为我们集成了<code>redux-thunk</code>和<code>redux-devtool</code>两个中间件</li></ul></li><li><code>devTools</code> 布尔值 是否启用开发者工具</li></ul><h2 id="使用rtk执行异步dispatch" tabindex="-1">使用RTK执行异步dispatch <a class="header-anchor" href="#使用rtk执行异步dispatch" aria-label="Permalink to &quot;使用RTK执行异步dispatch&quot;">​</a></h2><p>实际场景中都是在组件中发起网络请求，并且将状态更新到Store中</p><p>之前的开发中，我们通过<code>redux-thunk</code>这个中间件，让dispatch中可以进行异步操作</p><p>ReduxToolkit默认已经给我们集成了Thunk相关的功能：<code>createAsyncThunk</code></p><p>下面我们使用RTK实现一下这个场景：在Profile中请求postList数据并保存在Store中，并展示出来</p><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-ClSC-" id="tab-vBsjriE" checked="checked"><label for="tab-vBsjriE">postList.js</label><input type="radio" name="group-ClSC-" id="tab-Q3W1Gbs"><label for="tab-Q3W1Gbs">index.js</label><input type="radio" name="group-ClSC-" id="tab-x9YDi6I"><label for="tab-x9YDi6I">Profile.jsx</label></div><div class="blocks"><div class="language-tsx active 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;">// store/features/postList.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;">createSlice</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">createAsyncThunk</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;">@reduxjs/toolkit</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"></span>
<span class="line highlighted"><span style="color:#89DDFF;font-style:italic;">export</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> fetchPostList </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createAsyncThunk</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">fetch/postList</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">async</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 highlighted"><span style="color:#F07178;"> </span><span style="color:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">url</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;">https://jsonplaceholder.typicode.com/posts</span><span style="color:#89DDFF;">&#39;</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:#A6ACCD;">data</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">await</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">fetch</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">url</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:#A6ACCD;">res</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">json</span><span style="color:#F07178;">())</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">data</span></span>
<span class="line highlighted"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
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<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> postListSlice </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createSlice</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">postList</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;">initialState</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;">postList</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>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">reducers</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;">setPostList</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</span><span style="color:#A6ACCD;"> </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;">state</span><span style="color:#89DDFF;">.</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:#A6ACCD;">payload</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:#89DDFF;">},</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">extraReducers</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;">[</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">fulfilled</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#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;">payload</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">payload</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</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:#A6ACCD;">payload</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;">[</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">pending</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#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;">fetchPostList.pending</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">payload</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;">[</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">rejected</span><span style="color:#F07178;">]</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#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;">fetchPostList.rejected</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">payload</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:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> setPostList </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> postListSlice</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">actions</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;"> postListSlice</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">reducer</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><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;">// store/index.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;">configureStore</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;">@reduxjs/toolkit</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> counterReducer </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;">./features/counter</span><span style="color:#89DDFF;">&#39;</span></span>
<span class="line"><span style="color:#89DDFF;font-style:italic;">import</span><span style="color:#A6ACCD;"> postListReducer </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;">./features/postList</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:#82AAFF;">configureStore</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">reducer</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;">counter</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> counterReducer</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">postList</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> postListReducer</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:#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></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;">// 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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">connect</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-redux</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;">fetchPostList</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;">../store/features/postList</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;"> mapStateToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</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:#A6ACCD;"> </span><span style="color:#F07178;">postList</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">postList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">postList</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> mapDispatchToProps </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">dispatch</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:#A6ACCD;"> </span><span style="color:#82AAFF;">fetchPostList</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:#82AAFF;">dispatch</span><span style="color:#A6ACCD;">(</span><span style="color:#82AAFF;">fetchPostList</span><span style="color:#A6ACCD;">())</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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:#82AAFF;">connect</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapStateToProps</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;"> mapDispatchToProps</span></span>
<span class="line"><span style="color:#A6ACCD;">)(</span></span>
<span class="line"><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;"> Profile</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:#A6ACCD;">props</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">fetchPostList</span><span style="color:#A6ACCD;">()</span><span style="color:#89DDFF;">}&gt;</span><span style="color:#A6ACCD;">Fetch Data</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;">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;">props</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;">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;">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;">item</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:#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:#A6ACCD;"> </span><span style="color:#89DDFF;">}</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><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></div></div></div></div><p>当<code>createAsyncThunk</code>创建出来的action被dispatch时，会存在三种状态：</p><ul><li>pending: action被发出，但是还没有最终的结果</li><li>fulfilled: 获取到最终的结果（有返回值的结果）</li><li>rejected: 执行过程中又错误或者抛出了异常</li></ul><p>我们可以在<code>createSlice</code>的<code>entraReducer</code>中监听这些结果，根据派发action后的状态添加不同的逻辑进行处理</p><p>除了上述的写法，还可以为<code>extraReducer</code>传入一个函数，函数接收一个<code>builder</code>作为参数，在函数体内添加不同的case来监听异步操作的结果：</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:#676E95;font-style:italic;">// postList.js</span></span>
<span class="line"><span style="color:#89DDFF;">...</span></span>
<span class="line"><span style="color:#FFCB6B;">extraReducers</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">builder</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:#A6ACCD;">builder</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">addCase</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">fulfilled</span><span style="color:#89DDFF;">,</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:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">.</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:#A6ACCD;">payload</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:#A6ACCD;">builder</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">addCase</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">pending</span><span style="color:#89DDFF;">,</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:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#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;">fetchPostList.pending</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">payload</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:#A6ACCD;">builder</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">addCase</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">fetchPostList</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">rejected</span><span style="color:#89DDFF;">,</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:#89DDFF;">{</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</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:#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;">fetchPostList.rejected</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">payload</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:#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><p>在之前的代码中，我们都是通过触发action后置的回调来更新state，那么有没有可能在请求完毕时确定性地更新store中的state？</p><p>可以当请求有结果了，在请求成功的回调中直接dispatch设置state的action</p><p>当我们通过dispatch触发异步action时可以传递额外的参数，这些参数可以在传入createAsyncThunk的回调函数的参数中获取到，同时也可以从函数的参数中获取到<code>dispatch</code>与<code>getState</code>函数，这样就可以在请求到数据后直接通过派发action的方式更新store中的state，下面是修改后的例子：</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 has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// postList.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;">createSlice</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">createAsyncThunk</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;">@reduxjs/toolkit</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;"> fetchPostList </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createAsyncThunk</span><span style="color:#A6ACCD;">(</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">fetch/postList</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span></span>
<span class="line highlighted"><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">extraInfo</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">dispatch</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">getState</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:#C792EA;">const</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">url</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;">https://jsonplaceholder.typicode.com/posts</span><span style="color:#89DDFF;">&#39;</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;">data</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">await</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">fetch</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">url</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:#A6ACCD;">res</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">json</span><span style="color:#F07178;">())</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#82AAFF;">dispatch</span><span style="color:#F07178;">(</span><span style="color:#82AAFF;">setPostList</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">data</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>
<span class="line"></span>
<span class="line"><span style="color:#C792EA;">const</span><span style="color:#A6ACCD;"> postListSlice </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createSlice</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&#39;</span><span style="color:#C3E88D;">postList</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;">initialState</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;">postList</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>
<span class="line"><span style="color:#A6ACCD;"> </span><span style="color:#F07178;">reducers</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;">setPostList</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">state</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">payload</span><span style="color:#A6ACCD;"> </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;">state</span><span style="color:#89DDFF;">.</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:#A6ACCD;">payload</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:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</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;"> </span><span style="color:#89DDFF;">{</span><span style="color:#A6ACCD;"> setPostList </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> postListSlice</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">actions</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;"> postListSlice</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">reducer</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>当然，此时异步action的状态已经不那么重要了，也就不必再<code>return data</code>了，除非你需要对异常状态做额外处理，仍然可以在<code>extraReducers</code>中添加异常处理回调</p><h2 id="redux-toolkit的数据不可变性" tabindex="-1">Redux Toolkit的数据不可变性 <a class="header-anchor" href="#redux-toolkit的数据不可变性" aria-label="Permalink to &quot;Redux Toolkit的数据不可变性&quot;">​</a></h2><p>Redux Toolkit本质是对之前繁琐的操作进行的一次封装</p><p>我们注意到：在之前reducer对state进行更新时，必须返回一个新的state才能触发修改<code>state = { ...state, count: count + 1 }</code>，但是经过Redux Toolkit的封装，我们只需要<code>state.count += 1</code>，直接对状态进行赋值就可以完成状态的更新</p><p>这是因为在RTK内部使用了<code>immutable.js</code>，数据不可变性</p><ul><li>在React开发中，我们总是强调数据的不可变性 <ul><li>无论是类组件中的state还是redux中管理的state</li><li>JS的编码过程里，数据的不可变性都是非常重要的</li></ul></li><li>所以在之前我们更新state时都是通过浅拷贝来完成的 <ul><li>但是浅拷贝也存在它的缺陷：</li><li>当对象过大时，进行浅拷贝会造成性能的浪费</li><li>浅拷贝后的新对象，其深层属性仍然是旧对象的引用</li></ul></li></ul><p>Redux Toolkit底层使用了<code>immerjs</code>库来保证数据的不可变性</p><p>immutablejs库的底层原理和使用方法：<a href="https://mp.weixin.qq.com/s/hfeCDCcodBCGS5GpedxCGg" target="_blank" rel="noreferrer">React系列十八 - Redux(四)state如何管理</a></p><p>为了节约内存，出现了新的算法<code>Persistent Data Structure</code>持久化数据结构/一致性数据结构</p><ul><li>用一种数据结构来保存数据</li><li>当数据被修改时，会返回一个新的对象，但是新的对象会尽可能复用之前的数据结构而不会对内存进行浪费</li><li>比如有一棵引用层级较深的树，当我们对其深层某个节点进行修改时，不会完全拷贝整棵树，而是在尽可能复用旧树结构的同时创建一棵新的树</li></ul><p>一图胜千言：</p><p><img src="/assets/immutable.dc41f87b.gif" alt="immutable"></p><h2 id="connect的实现原理" tabindex="-1">connect的实现原理 <a class="header-anchor" href="#connect的实现原理" aria-label="Permalink to &quot;connect的实现原理&quot;">​</a></h2><p>connect函数是<code>react-redux</code>提供的一个高阶函数，它返回一个高阶组件，用于将store中的state/dispatch映射为组件的props</p><p>下面一步一步手写一个connect函数，实现和库提供的connect一样的映射功能：</p><p>首先完成基本的代码搭建，connect函数接收两个参数<code>mapStateToProps</code> <code>mapDispatchToProps</code>返回一个高阶组件</p><p>所谓高阶组件，就是传入一个类组件，返回一个增强后的新的类组件：</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"><code><span class="line"><span style="color:#676E95;font-style:italic;">// connect.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;">PureComponent</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;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">connect</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">mapStateToProps</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">mapDispatchToProps</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:#A6ACCD;font-style:italic;">WrapperComponent</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">class</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">InnerComponent</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">extends</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">PureComponent</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> render</span><span style="color:#89DDFF;">()</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 style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">WrapperComponent</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:#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:#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></div></div><p>其中，<code>mapStateToProps</code>和<code>mapDispatchToProps</code>都是函数，函数入参是<code>state</code>与<code>dispatch</code>，返回一个对象，键值对对应<code>prop &lt;=&gt; state/dispatch调用</code></p><p>我们导入store，并且从store中获取到state和dispatch传入<code>mapStateToProps</code>和<code>mapDispatchToProps</code>，随后将得到的键值对以props形式传递给WrapperComponent</p><p>这样新组件就可以拿到这些状态与dispatch方法，我们可以在<code>componentDidMount</code>中监听整个store，当store中的状态发生改变时，强制执行re-render</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;">// connect.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;">PureComponent</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;"> store </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;">../store</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;">connect</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">mapStateToProps</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">mapDispatchToProps</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:#A6ACCD;font-style:italic;">WrapperComponent</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">class</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">InnerComponent</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">extends</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">PureComponent</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> componentDidMount</span><span style="color:#89DDFF;">()</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">subscribe</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:#89DDFF;">this.</span><span style="color:#82AAFF;">forceUpdate</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:#F07178;"> render</span><span style="color:#89DDFF;">()</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;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#F07178;">())</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;">dispatch</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapDispatchToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</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:#FFCB6B;">WrapperComponent</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} {...</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">} {...</span><span style="color:#A6ACCD;">dispatch</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:#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></div></div><p>上述代码能够正常工作，但是显然每次store内state发生改变都re-render是不明智的，因为组件可能只用到了store中的某些状态</p><p>那些组件没有用到的其他状态发生改变时，组件不应该也跟着re-render，这里可以做一些优化</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 has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// connect.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;">PureComponent</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;"> store </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;">../store</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;">connect</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">mapStateToProps</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">mapDispatchToProps</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:#A6ACCD;font-style:italic;">WrapperComponent</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">class</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">InnerComponent</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">extends</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">PureComponent</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">props</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </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 style="color:#A6ACCD;">props</span><span style="color:#F07178;">)</span></span>
<span class="line highlighted"><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:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</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:#F07178;"> componentDidMount</span><span style="color:#89DDFF;">()</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">subscribe</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:#89DDFF;">{</span></span>
<span class="line highlighted"><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:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#F07178;">()))</span></span>
<span class="line highlighted"><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:#F07178;"> render</span><span style="color:#89DDFF;">()</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;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#F07178;">())</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;">dispatch</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapDispatchToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</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 style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">WrapperComponent</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{...</span><span style="color:#FFCB6B;">this</span><span style="color:#89DDFF;">.</span><span style="color:#FFCB6B;">props</span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{...</span><span style="color:#FFCB6B;">state</span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{...</span><span style="color:#FFCB6B;">dispatch</span><span style="color:#89DDFF;">}</span><span style="color:#F07178;"> /</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>
<span class="line"><span style="color:#F07178;">}</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>经过优化后，每次store.state发生变化会触发setState，由React内部的机制来决定组件是否应当重新渲染</p><p>如果组件依赖的state发生变化了，那么React会替我们执行re-render，而不是每次都强制执行re-render</p><p>进一步地，我们可以补充更多细节：</p><ul><li>当组件卸载时解除监听 <ul><li><code>store.subscribe</code>会返回一个<code>unsubscribe</code>函数 用于解除监听</li></ul></li><li>解除与业务代码store的耦合 <ul><li>目前的store来自业务代码 更优的做法是从context中动态获取到store</li><li>应当提供一个context Provider供用户使用</li><li>就像<code>react-redux</code>一样，使用connect前需要将App用Provider包裹并传入store</li></ul></li></ul><p>至此就基本完成了一个connect函数</p><div class="vp-code-group"><div class="tabs"><input type="radio" name="group-H6teW" id="tab-ztxmVTc" checked="checked"><label for="tab-ztxmVTc">connect.js</label><input type="radio" name="group-H6teW" id="tab-YNJ5Knp"><label for="tab-YNJ5Knp">storeContext.js</label><input type="radio" name="group-H6teW" id="tab-rIUf8UP"><label for="tab-rIUf8UP">App.jsx</label></div><div class="blocks"><div class="language-tsx active 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;">// connect.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;">PureComponent</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;">StoreContext</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;">./storeContext</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;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">connect</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">mapStateToProps</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#A6ACCD;font-style:italic;">mapDispatchToProps</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:#A6ACCD;font-style:italic;">WrapperComponent</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;">class</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">InnerComponent</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">extends</span><span style="color:#F07178;"> </span><span style="color:#FFCB6B;">PureComponent</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">constructor</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">props</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;font-style:italic;">context</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </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 style="color:#A6ACCD;">props</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:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">context</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</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:#F07178;"> componentDidMount</span><span style="color:#89DDFF;">()</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:#A6ACCD;">unsubscribe</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;">context</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">subscribe</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:#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:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">context</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</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:#F07178;"> componentWillUnmount</span><span style="color:#89DDFF;">()</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;">unsubscribe</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:#F07178;"> render</span><span style="color:#89DDFF;">()</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;">state</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapStateToProps</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">context</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</span><span style="color:#F07178;">())</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;">dispatch</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">mapDispatchToProps</span><span style="color:#F07178;">(</span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">context</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</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 style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">WrapperComponent</span><span style="color:#89DDFF;"> {...this.</span><span style="color:#A6ACCD;">props</span><span style="color:#89DDFF;">} {...</span><span style="color:#A6ACCD;">state</span><span style="color:#89DDFF;">} {...</span><span style="color:#A6ACCD;">dispatch</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:#F07178;"> </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">InnerComponent</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">contextType</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">StoreContext</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:#A6ACCD;">InnerComponent</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></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;">// storeContext.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;"> StoreContext </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">createContext</span><span style="color:#A6ACCD;">(</span><span style="color:#89DDFF;">null</span><span style="color:#A6ACCD;">)</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;"> Provider </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> StoreContext</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">Provider</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></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;">// 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;"> store </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;">./store</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;">./cpns/Counter</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;">Provider</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;">./hoc</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:#FFCB6B;">Provider</span><span style="color:#89DDFF;"> </span><span style="color:#C792EA;">value</span><span style="color:#89DDFF;">={</span><span style="color:#A6ACCD;">store</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;">h1</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;">React Redux</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:#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:#A6ACCD;"> </span><span style="color:#89DDFF;">&lt;/</span><span style="color:#FFCB6B;">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></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></div></div><h2 id="实现日志中间件logger" tabindex="-1">实现日志中间件logger <a class="header-anchor" href="#实现日志中间件logger" aria-label="Permalink to &quot;实现日志中间件logger&quot;">​</a></h2><p>设想现在有需求：设计一个Redux中间件，当我们每次通过dispatch派发action时都能够在控制台输出：派发了哪个action，传递的数据是怎样的</p><p>最终实现：拦截dispatch，并且在控制台打印派发的action</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:#676E95;font-style:italic;">// logger.js</span></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">logger</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">store</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;">next</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</span><span style="color:#F07178;"> </span><span style="color:#676E95;font-style:italic;">// 保留原始的dispatch函数</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">function</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">dispatchWithLog</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">action</span><span style="color:#89DDFF;">)</span><span style="color:#F07178;"> </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;">group</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">action</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">type</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;">dispatching</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</span><span style="color:#F07178;">)</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;">res</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">next</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">dispatch</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">action</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;">next state</span><span style="color:#89DDFF;">&#39;</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">getState</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;">groupEnd</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:#A6ACCD;">res</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:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">dispatchWithLog</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">logger</span><span style="color:#A6ACCD;">(store) </span><span style="color:#676E95;font-style:italic;">// 应用中间件</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>通过<code>monkey patch</code>对原始dispatch函数进行了修改，为函数添加额外的副作用</p><h2 id="实现redux-thunk" tabindex="-1">实现redux-thunk <a class="header-anchor" href="#实现redux-thunk" aria-label="Permalink to &quot;实现redux-thunk&quot;">​</a></h2><p><code>redux-thunk</code>这个库帮我们提供了派发异步函数的功能</p><p>回顾一下<code>redux-thunk</code>的功能：</p><ul><li>默认情况下dispatch(action)的action必须为一个JS对象</li><li>redux-thunk允许我们传入一个函数作为action</li><li>函数会被调用，并且将dispatch函数和getState函数作为入参传递给这个函数action <ul><li>dispatch 允许我们在这之后再次派发action</li><li>getState 允许我们之后的一些操作依赖原来的状态，可以获取到之前的状态</li></ul></li></ul><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 has-highlighted-lines"><code><span class="line"><span style="color:#676E95;font-style:italic;">// thunk.js</span></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">thunk</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">store</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;">next</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</span></span>
<span class="line"><span style="color:#F07178;"> </span><span style="color:#C792EA;">function</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">dispatchWithThunk</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">action</span><span style="color:#89DDFF;">)</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;">if</span><span style="color:#F07178;"> (</span><span style="color:#89DDFF;">typeof</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">action</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;">function</span><span style="color:#89DDFF;">&#39;</span><span style="color:#F07178;">) </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#89DDFF;"> </span><span style="color:#676E95;font-style:italic;">// pass dispatch and getState to the thunk</span></span>
<span class="line highlighted"><span style="color:#F07178;"> </span><span style="color:#89DDFF;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">action</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">dispatch</span><span style="color:#89DDFF;">,</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">store</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">getState</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;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">next</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">action</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;font-style:italic;">return</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">dispatchWithThunk</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#82AAFF;">thunk</span><span style="color:#A6ACCD;">(store) </span><span style="color:#676E95;font-style:italic;">// 应用中间件</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><p>需要注意的是，传递给函数action的第一个参数是经过更新后的新的<code>dispatch</code>函数，这是从细节考虑：如果在函数中又派发了函数</p><h2 id="实现applymiddleware" tabindex="-1">实现applyMiddleware <a class="header-anchor" href="#实现applymiddleware" aria-label="Permalink to &quot;实现applyMiddleware&quot;">​</a></h2><p>当我们需要同时应用多个中间件时，可以用<code>applyMiddleware</code>来对多个中间件进行组合，统一进行注册</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:#676E95;font-style:italic;">// applyMiddleware.js</span></span>
<span class="line"><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">applyMiddleware</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">store</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">...</span><span style="color:#A6ACCD;font-style:italic;">fns</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;">fns</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">forEach</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;font-style:italic;">fn</span><span style="color:#F07178;"> </span><span style="color:#C792EA;">=&gt;</span><span style="color:#F07178;"> </span><span style="color:#82AAFF;">fn</span><span style="color:#F07178;">(</span><span style="color:#A6ACCD;">store</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;">applyMiddleware</span><span style="color:#A6ACCD;">(store</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> logger</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> thunk) </span><span style="color:#676E95;font-style:italic;">// 使用applyMiddleware</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></div></div></div></div></main><footer class="VPDocFooter" data-v-f0e11dcf data-v-bdb4c5a7><!--[--><!--]--><div class="edit-info" data-v-bdb4c5a7><div class="edit-link" data-v-bdb4c5a7><a class="VPLink link vp-external-link-icon no-icon edit-link-button" href="https://github.com/ZiuChen/ZiuChen.github.io/edit/main/docs/note/Redux.md" target="_blank" rel="noreferrer" data-v-bdb4c5a7><!--[--><svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 24 24" class="edit-link-icon" aria-label="edit icon" data-v-bdb4c5a7><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-bdb4c5a7><p class="VPLastUpdated" data-v-bdb4c5a7 data-v-4e6de435>Updated Date: <time datetime="2023-07-16T12:21:50.000Z" data-v-4e6de435></time></p></div></div><nav class="prev-next" data-v-bdb4c5a7><div class="pager" data-v-bdb4c5a7><a class="pager-link prev" href="/note/React%20Hooks.html" data-v-bdb4c5a7><span class="desc" data-v-bdb4c5a7>Previous page</span><span class="title" data-v-bdb4c5a7>React Hooks</span></a></div><div class="pager" data-v-bdb4c5a7><a class="pager-link next" href="/note/React%20Router.html" data-v-bdb4c5a7><span class="desc" data-v-bdb4c5a7>Next page</span><span class="title" data-v-bdb4c5a7>React Router</span></a></div></nav></footer><!--[--><!--]--></div></div></div><!--[--><!--]--></div></div><footer class="VPFooter has-sidebar" data-v-4b282efc data-v-a21bf57e><div class="container" data-v-a21bf57e><p class="message" data-v-a21bf57e>Released under the MIT License.</p><p class="copyright" data-v-a21bf57e>Copyright © 2019-present Ziu Chen</p></div></footer><!--[--><!--]--></div></div>
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