---
title: Set.prototype.has()
slug: Web/JavaScript/Reference/Global_Objects/Set/has
tags:
  - ECMAScript 2015
  - JavaScript
  - set
translation_of: Web/JavaScript/Reference/Global_Objects/Set/has
---
<div>{{JSRef("Global_Objects", "Set")}}</div>

<h2 id="Summary">概述</h2>

<p><strong>has() </strong>方法返回一个布尔值来指示对应的值value是否存在Set对象中。</p>

<h2 id="Syntax">语法</h2>

<pre class="syntaxbox"><code><em>mySet</em>.has(value);</code></pre>

<h3 id="参数">参数</h3>

<dl>
 <dt>value</dt>
 <dd>必需。用以测试该值是否存在于 Set 对象中。</dd>
</dl>

<h3 id="返回值">返回值</h3>

<dl>
 <dt>Boolean</dt>
 <dd>如果指定的值（value）存在于Set对象当中，返回<code>true</code>；否则返回 <code>false</code>。</dd>
</dl>

<h2 id="Examples">示例</h2>

<h3 id="Example:_Testing_size_of_all_array_elements">使用 <code>has</code> 方法</h3>

<pre class="brush: js line-numbers  language-js">var mySet = new Set();
mySet.add('foo');

mySet.has('foo');  // 返回 true
mySet.has('bar');  // 返回 false

var set1 = new Set();
var obj1 = {'key1': 1};
set1.add(obj1);

set1.has(obj1);        // 返回 true
set1.has({'key1': 1}); // 会返回 false，因为其是另一个对象的引用
set1.add({'key1': 1}); // 现在 set1 中有2条（不同引用的）对象了</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-set.prototype.has', 'Set.prototype.has')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{ CompatibilityTable() }}</p>

<div>
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>38</td>
   <td>{{CompatGeckoDesktop("13.0")}}</td>
   <td>11</td>
   <td>25</td>
   <td>7.1</td>
  </tr>
 </tbody>
</table>
</div>

<div>
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{ CompatNo() }}</td>
   <td>38</td>
   <td>{{CompatGeckoMobile("13.0")}}</td>
   <td>{{ CompatNo() }}</td>
   <td>{{ CompatNo() }}</td>
   <td>iOS 8</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="相关连接"><strong>相关连接</strong></h2>

<ul>
 <li>{{jsxref("Set")}}</li>
 <li>{{jsxref("Set.prototype.add()")}}</li>
 <li>{{jsxref("Set.prototype.delete()")}}</li>
</ul>