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语法高亮，滚动条美化，设置页面调整

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docs/javascript/Reference/Operators/in.html
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@@ -2,7 +2,7 @@
<p></p><p></p>
<p>如果指定的属性在指定的对象或其原型链中，则<strong><code>in</code> 运算符</strong>返回<code>true</code>。</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><em>prop</em> in <em>object</em></pre>
<pre><code class="language-javascript"><em>prop</em> in <em>object</em></code></pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
<dt><code>prop</code></dt>
@@ -14,7 +14,7 @@
</dl>
<h2 id="Description" name="Description">描述</h2>
<p>下面的例子演示了一些 <code>in</code> 运算符的用法。</p>
<pre class="brush:js">// 数组
<pre><code class="language-js">// 数组
var trees = new Array("redwood", "bay", "cedar", "oak", "maple");
0 in trees // 返回true
3 in trees // 返回true
@@ -33,36 +33,36 @@ Symbol.iterator in trees // 返回true (数组可迭代，只在ES2015+上有效
var mycar = {make: "Honda", model: "Accord", year: 1998};
"make" in mycar // 返回true
"model" in mycar // 返回true
</pre>
</code></pre>
<p><code>in</code>右操作数必须是一个对象值。例如，你可以指定使用<code>String</code>构造函数创建的字符串，但不能指定字符串文字。</p>
<pre class="brush:js">var color1 = new String("green");
<pre><code class="language-js">var color1 = new String("green");
"length" in color1 // 返回true
var color2 = "coral";
"length" in color2 // 报错(color2不是对象)
</pre>
</code></pre>
<h3 id="Using_in_with_deleted_or_undefined_properties" name="Using_in_with_deleted_or_undefined_properties">对被删除或值为 undefined 的属性使用<code>in</code></h3>
<p>如果你使用 <code><a href="/zh-CN/docs/JavaScript/Reference/Operators/delete" title="zh-CN/docs/JavaScript/Reference/Operators/Special/delete">delete</a></code> 运算符删除了一个属性，则 <code>in</code> 运算符对所删除属性返回 <code>false</code>。</p>
<pre class="brush:js">var mycar = {make: "Honda", model: "Accord", year: 1998};
<pre><code class="language-js">var mycar = {make: "Honda", model: "Accord", year: 1998};
delete mycar.make;
"make" in mycar; // 返回false
var trees = new Array("redwood", "bay", "cedar", "oak", "maple");
delete trees[3];
3 in trees; // 返回false
</pre>
</code></pre>
<p>如果你只是将一个属性的值赋值为<a href="Reference/Global_Objects/undefined" title="undefined是全局对象的一个属性。也就是说，它是全局作用域的一个变量。undefined的最初值就是原始数据类型undefined。"><code>undefined</code></a>，而没有删除它，则 <code>in</code> 运算仍然会返回<code>true</code>。</p>
<pre class="brush:js">var mycar = {make: "Honda", model: "Accord", year: 1998};
<pre><code class="language-js">var mycar = {make: "Honda", model: "Accord", year: 1998};
mycar.make = undefined;
"make" in mycar; // 返回true
</pre>
<pre class="brush:js">var trees = new Array("redwood", "bay", "cedar", "oak", "maple");
</code></pre>
<pre><code class="language-js">var trees = new Array("redwood", "bay", "cedar", "oak", "maple");
trees[3] = undefined;
3 in trees; // 返回true
</pre>
</code></pre>
<h3 id="Inherited_properties" name="Inherited_properties">继承属性</h3>
<p>如果一个属性是从原型链上继承来的，<code>in</code> 运算符也会返回 <code>true</code>。</p>
<pre class="brush:js">"toString" in {}; // 返回true
</pre>
<pre><code class="language-js">"toString" in {}; // 返回true
</code></pre>
<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2>
<table class="standard-table">
<tbody>