---
title: HTMLMediaElement.duration
slug: Web/API/HTMLMediaElement/duration
tags:
  - API
  - HTML
  - Video
  - Web
translation_of: Web/API/HTMLMediaElement/duration
---
<div>{{APIRef("HTML DOM")}}</div>

<p><strong><code>HTMLMediaElement.duration</code></strong> 属性以秒为单位给出媒体的长度，如果没有媒体数据可用，则为零。</p>

<h2 id="Syntax" name="Syntax">语法</h2>

<pre class="brush: js">var <em>myDuration</em> = <em>audioOrVideo</em>.duration</pre>

<h3 id="值">值</h3>

<p> 如果媒体数据可用但长度未知，则此值为NaN。 如果媒体流式传输且没有预定义长度，则值为Inf。</p>

<h2 id="例子">例子</h2>

<pre class="brush: js">var obj = document.createElement('video');
console.log(obj.duration); // NaN
</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">规范</th>
   <th scope="col">状态</th>
   <th scope="col">注释</th>
  </tr>
  <tr>
   <td>{{SpecName('HTML WHATWG', "the-video-element.html#htmlmediaelement", "HTMLMediaElement.duration")}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td>No change from {{SpecName('HTML5 W3C')}}</td>
  </tr>
  <tr>
   <td>{{SpecName('HTML5 W3C', "embedded-content-0.html#htmlmediaelement", "HTMLMediaElement.duration")}}</td>
   <td>{{Spec2('HTML5 W3C')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器支持">浏览器支持</h2>

<p>{{Compat("api.HTMLMediaElement.duration")}}</p>

<h2 id="See_Also" name="See_Also">相关内容</h2>

<ul>
 <li>定义它的接口， {{domxref("HTMLMediaElement")}}.</li>
</ul>