ZiuChen.github.io/assets/article_彻底搞懂对象的数据属性描述符、存储属性描述符.md.c734a50f.js

import{_ as s,o as n,c as a,R as l}from"./chunks/framework.a304f0f7.js";const C=JSON.parse('{"title":"彻底搞懂对象的数据属性描述符、存储属性描述符","description":"","frontmatter":{},"headers":[],"relativePath":"article/彻底搞懂对象的数据属性描述符、存储属性描述符.md","lastUpdated":1682215244000}'),p={name:"article/彻底搞懂对象的数据属性描述符、存储属性描述符.md"},o=l(`<h1 id="彻底搞懂对象的数据属性描述符、存储属性描述符" tabindex="-1">彻底搞懂对象的数据属性描述符、存储属性描述符 <a class="header-anchor" href="#彻底搞懂对象的数据属性描述符、存储属性描述符" aria-label="Permalink to &quot;彻底搞懂对象的数据属性描述符、存储属性描述符&quot;">​</a></h1><h2 id="属性描述符" tabindex="-1">属性描述符 <a class="header-anchor" href="#属性描述符" aria-label="Permalink to &quot;属性描述符&quot;">​</a></h2><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> obj </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;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">ziu</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">age</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">18</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">  Object</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">defineProperty</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">height</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">value</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">1.88</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj) </span><span style="color:#676E95;font-style:italic;">// { name: &#39;ziu&#39;, age: 18 }</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><p><code>obj</code>对象的控制台输出中，并没有<code>defineProperty</code>新定义的<code>height</code>，这是因为不可枚举的（不可遍历的），在打印时并没有和其他属性一起输出。这个属性已经被添加到对象中，只不过不可见。</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#A6ACCD;">console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">height) </span><span style="color:#676E95;font-style:italic;">// 1.88</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><p>属性描述符是一个对象，根据功能不同，可以分为两类：<strong>数据属性描述符</strong>和<strong>存储属性描述符</strong></p><h3 id="数据属性描述符" tabindex="-1">数据属性描述符 <a class="header-anchor" href="#数据属性描述符" aria-label="Permalink to &quot;数据属性描述符&quot;">​</a></h3><ul><li>数据属性描述符（Data Properties） <ul><li><code>value</code>该属性对应的值，默认<code>undefined</code></li><li><code>configurable</code>该属性描述符是否可被改变、是否可被删除，默认为<code>false</code></li><li><code>enumerable</code>该属性是否可被枚举，默认为<code>false</code></li><li><code>writable</code>该属性是否可以被写入新的值，默认为<code>false</code></li></ul></li></ul><p><strong>没有用属性描述符定义的对象属性（直接使用<code>.</code>语法）</strong>，也是具有以上属性描述符的特性的，<code>value</code>值为属性被赋值的值，其他<code>configurable</code>、<code>emumerable</code>、<code>writable</code>默认值都为<code>true</code>。<strong>注意，属性描述符区全为小写。</strong></p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> obj </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;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">ziu</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">age</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">18</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:#676E95;font-style:italic;">// 数据属性描述符</span></span>
<span class="line"><span style="color:#A6ACCD;">  Object</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">defineProperty</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">address</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">value</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Beijing</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// 该属性对应的值，默认为undefine</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">configurable</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FF9CAC;">false</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// 该属性描述符是否可被改变、是否可被删除，默认为false</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">enumerable</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FF9CAC;">true</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// 该属性是否可被枚举，默认为false</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">writable</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FF9CAC;">true</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// 该属性是否可以被写入新的值，默认为false</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;">)</span></span>
<span class="line"><span style="color:#89DDFF;">  </span><span style="color:#676E95;font-style:italic;">// configurable</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#89DDFF;">delete</span><span style="color:#A6ACCD;"> obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address</span></span>
<span class="line"><span style="color:#A6ACCD;">  obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Shanghai</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address) </span><span style="color:#676E95;font-style:italic;">// Beijing</span></span>
<span class="line"><span style="color:#89DDFF;">  </span><span style="color:#676E95;font-style:italic;">// enumerable</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj)</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#89DDFF;font-style:italic;">for</span><span style="color:#A6ACCD;">(</span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> key </span><span style="color:#89DDFF;">in</span><span style="color:#A6ACCD;"> obj) </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:#A6ACCD;">key</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;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(Object</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">keys</span><span style="color:#A6ACCD;">(obj))</span></span>
<span class="line"><span style="color:#89DDFF;">  </span><span style="color:#676E95;font-style:italic;">// writable</span></span>
<span class="line"><span style="color:#A6ACCD;">  obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Tianjin</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><h3 id="存储属性描述符" tabindex="-1">存储属性描述符 <a class="header-anchor" href="#存储属性描述符" aria-label="Permalink to &quot;存储属性描述符&quot;">​</a></h3><ul><li>存储属性描述符（Accessor Properties） <ul><li><code>get</code>当访问该属性时，会调用此函数，默认为<code>undefined</code>。</li><li><code>set</code>当属性值被修改时，会调用此函数，默认为<code>undefined</code>。</li></ul></li></ul><p>注意，<code>get</code>、<code>set</code>描述符与<code>vaule</code>、<code>writable</code>描述符不共存。</p><table><thead><tr><th></th><th><code>configurable</code></th><th><code>enumerable</code></th><th><code>value</code></th><th><code>writable</code></th><th><code>get</code></th><th><code>set</code></th></tr></thead><tbody><tr><td>数据描述符</td><td>可以</td><td>可以</td><td>可以</td><td>可以</td><td><strong>不可以</strong></td><td><strong>不可以</strong></td></tr><tr><td>存取描述符</td><td>可以</td><td>可以</td><td><strong>不可以</strong></td><td><strong>不可以</strong></td><td>可以</td><td>可以</td></tr></tbody></table><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> obj </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;">name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">ziu</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">age</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">18</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">_address</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Beijing</span><span style="color:#89DDFF;">&quot;</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:#676E95;font-style:italic;">// Accessor Properties</span></span>
<span class="line"><span style="color:#A6ACCD;">  Object</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">defineProperty</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">address</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">enumerable</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FF9CAC;">true</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F07178;">configurable</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FF9CAC;">true</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#89DDFF;">    </span><span style="color:#676E95;font-style:italic;">// value: &quot;Beijing&quot;,</span></span>
<span class="line"><span style="color:#89DDFF;">    </span><span style="color:#676E95;font-style:italic;">// writable: true,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">get</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</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;">this.</span><span style="color:#A6ACCD;">_address</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;">set</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">val</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#F07178;">        </span><span style="color:#89DDFF;">this.</span><span style="color:#A6ACCD;">_address</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">val</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 style="color:#A6ACCD;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address) </span><span style="color:#676E95;font-style:italic;">// 调用getter() Beijing</span></span>
<span class="line"><span style="color:#A6ACCD;">  obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Shanghai</span><span style="color:#89DDFF;">&quot;</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// 调用setter()</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">_address) </span><span style="color:#676E95;font-style:italic;">// Shanghai</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></div></div><h3 id="应用场景" tabindex="-1">应用场景 <a class="header-anchor" href="#应用场景" aria-label="Permalink to &quot;应用场景&quot;">​</a></h3><ol><li>隐藏某个私有属性，希望直接被外界使用和赋值。（下划线开头的变量一般为私有属性）</li><li>获取某个属性被访问或赋值的时刻，可以设置伴随被访问或被赋值时，执行其他函数。</li></ol><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#A6ACCD;">Object</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">defineProperty</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">address</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">get</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</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:#82AAFF;">bar</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;">this.</span><span style="color:#A6ACCD;">_address</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;">set</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">function</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;font-style:italic;">val</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:#82AAFF;">foo</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;">_address</span><span style="color:#F07178;"> </span><span style="color:#89DDFF;">=</span><span style="color:#F07178;"> </span><span style="color:#A6ACCD;">val</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 style="color:#A6ACCD;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">  console</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">log</span><span style="color:#A6ACCD;">(obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address) </span><span style="color:#676E95;font-style:italic;">// got address value once</span></span>
<span class="line"><span style="color:#A6ACCD;">  obj</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">address </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Shanghai</span><span style="color:#89DDFF;">&quot;</span><span style="color:#A6ACCD;"> </span><span style="color:#676E95;font-style:italic;">// resetted address value once</span></span>
<span class="line"><span style="color:#A6ACCD;">  </span><span style="color:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">bar</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;">&quot;</span><span style="color:#C3E88D;">got address value once</span><span style="color:#89DDFF;">&quot;</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:#C792EA;">function</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">foo</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;">&quot;</span><span style="color:#C3E88D;">resetted address value once</span><span style="color:#89DDFF;">&quot;</span><span style="color:#F07178;">)</span></span>
<span class="line"><span style="color:#F07178;">  </span><span style="color:#89DDFF;">}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div>`,18),e=[o];function t(c,r,D,y,F,i){return n(),a("div",null,e)}const d=s(p,[["render",t]]);export{C as __pageData,d as default};