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

<div></div>

<div><code>deref</code>方法返回{{jsxref("WeakRef")}} 实例的目标对象，如果目标对象已被垃圾收集，则返回<code>undefined</code> 。</div>

<h2 id="语法">语法</h2>

<pre class="syntaxbox notranslate"><code><var>obj</var> = <var>ref</var>.deref();</code>
</pre>

<h3 id="返回值">返回值</h3>

<p>返回WeakRef的目标对象，如果该对象已被垃圾收集，则返回<code>undefined</code> 。</p>

<h2 id="说明">说明</h2>

<p>有关一些重要说明，请参阅{{jsxref("WeakRef")}}页面上的<a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakRef#Notes_on_WeakRefs">Notes on WeakRefs</a> 。</p>

<h2 id="例子">例子</h2>

<h3 id="使用deref">使用deref</h3>

<p>有关<a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakRef#Examples">完整示例</a>，请参阅{{jsxref("WeakRef")}}页面的示例部分。</p>

<pre class="brush: js notranslate">const tick = () =&gt; {
  // Get the element from the weak reference, if it still exists
  const element = this.ref.deref();
  if (element) {
    element.textContent = ++this.count;
  } else {
    // The element doesn't exist anymore
    console.log("The element is gone.");
    this.stop();
    this.ref = null;
  }
};</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">规范</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('WeakRefs', '#sec-weak-ref.prototype.deref', 'WeakRef.prototype.deref()')}}</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>



<p>{{Compat("javascript.builtins.WeakRef.deref")}}</p>

<h2 id="相关链接">相关链接</h2>

<ul>
 <li>{{jsxref("WeakRef")}}</li>
</ul>