---
title: WeakSet.prototype.has()
slug: Web/JavaScript/Reference/Global_Objects/WeakSet/has
translation_of: Web/JavaScript/Reference/Global_Objects/WeakSet/has
---
<div>{{JSRef}}</div>

<p><code><strong>has()</strong></code> 方法根据 <code>WeakSet</code> 是否存在相应对象返回布尔值。</p>

<h2 id="语法">语法</h2>

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

<h3 id="参数">参数</h3>

<dl>
 <dt>value</dt>
 <dd>必须。 测试 <code>WeakSet 中是否存在该对象。</code></dd>
</dl>

<h3 id="返回值">返回值</h3>

<dl>
 <dt>Boolean</dt>
 <dd>如果 <code>WeakSet</code> 对象中存在指定的元素，返回 true；否则返回 <code>false。</code></dd>
</dl>

<h2 id="示例">示例</h2>

<h3 id="使用_has_方法">使用 <code>has</code> 方法</h3>

<pre class="brush: js">var ws = new WeakSet();
var obj = {};
ws.add(window);

mySet.has(window);  // 返回 true
mySet.has(obj);     // 返回 false
</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-weakset.prototype.has', 'WeakSet.prototype.has')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-weakset.prototype.has', 'WeakSet.prototype.has')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<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>36</td>
   <td>{{CompatGeckoDesktop(34)}}</td>
   <td>{{CompatNo}}</td>
   <td>23</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>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>{{ CompatGeckoMobile(34) }}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="相关链接">相关链接</h2>

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