files/zh-cn/web/javascript/reference/global_objects/object/count/index.html


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---
title: Object.prototype.__count__
slug: Web/JavaScript/Reference/Global_Objects/Object/count
tags:
  - JavaScript
  - Object
  - Obsolete
  - Property
  - Prototype
translation_of: Archive/Web/JavaScript/Object.count
---
<div>{{JSRef}} {{obsolete_header("2")}}</div>

<p> <strong><code>__count__</code></strong> 属性曾经用来存放对象的可枚举的属性的个数，但是已经被废除。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox"><code><var>obj</var>.__count__</code></pre>

<h2 id="示例">示例</h2>

<pre class="brush: js">{ 1: 1 }.__count__              // 1
[].__count__                    // 0
[1].__count__                   // 1
[1, /* hole */, 2, 3].__count__ // 3
</pre>

<h2 id="详细说明">详细说明</h2>

<p>无需详细说明</p>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<div>{{CompatibilityTable}}</div>

<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>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</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>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>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="更多请参看">更多请参看</h2>

<ul>
 <li><a class="external" href="http://whereswalden.com/2010/04/06/more-changes-coming-to-spidermonkey-the-magical-__count__-property-of-objects-is-being-removed/">[Blog post] More changes coming to SpiderMonkey: the magical __count__ property is being removed</a></li>
</ul>