---
title: devicechange
slug: Web/API/MediaDevices/devicechange_event
translation_of: Web/API/MediaDevices/devicechange_event
---
<p>每当媒体设备（例如相机，麦克风或扬声器）连接到系统或从系统中移除时，<code>devicechange </code>事件就会被发送到 {{domxref("MediaDevices")}}  实例。 这是一个没有附加属性的通用 {{domxref("Event")}} 。</p>

<h2 id="一般信息">一般信息</h2>

<dl>
 <dt style="float: left; text-align: right; width: 120px;">规范</dt>
 <dd style="margin: 0 0 0 120px;">{{SpecName('Media Capture')}}</dd>
 <dt style="float: left; text-align: right; width: 120px;">接口</dt>
 <dd style="margin: 0 0 0 120px;">Event</dd>
 <dt style="float: left; text-align: right; width: 120px;">是否冒泡</dt>
 <dd style="margin: 0 0 0 120px;">No</dd>
 <dt style="float: left; text-align: right; width: 120px;">是否可取消</dt>
 <dd style="margin: 0 0 0 120px;">No</dd>
 <dt style="float: left; text-align: right; width: 120px;">对象</dt>
 <dd style="margin: 0 0 0 120px;">{{domxref('MediaDevices')}}</dd>
 <dt style="float: left; text-align: right; width: 120px;">默认动作</dt>
 <dd style="margin: 0 0 0 120px;">None</dd>
</dl>

<h2 id="属性">属性</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Property</th>
   <th scope="col">Type</th>
   <th scope="col">Description</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td><code>target</code>{{readonlyinline}}</td>
   <td>{{domxref("EventTarget")}}</td>
   <td>事件对象 (位于DOM树最上面的元素).</td>
  </tr>
  <tr>
   <td><code>type</code> {{readonlyinline}}</td>
   <td>{{domxref("DOMString")}}</td>
   <td>事件类型.</td>
  </tr>
  <tr>
   <td><code>bubbles</code> {{readonlyinline}}</td>
   <td>{{domxref("Boolean")}}</td>
   <td>是否冒泡</td>
  </tr>
  <tr>
   <td><code>cancelable</code> {{readonlyinline}}</td>
   <td>{{domxref("Boolean")}}</td>
   <td>是否可被取消</td>
  </tr>
 </tbody>
</table>

<h2 id="相关事件">相关事件</h2>

<p><em>无</em>.</p>

<h2 id="样例">样例</h2>

<p>有关使用 <code>devicechange</code> 事件更新屏幕上设备列表的示例，请参阅 {{SectionOnPage("/en-US/docs/Web/API/MediaDevices/ondevicechange", "Example")}}。</p>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{ SpecName('Media Capture', '#event-mediadevices-devicechange', 'devicechange') }}</td>
   <td>{{ Spec2('Media Capture') }}</td>
   <td>Initial specification.</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>Edge</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(52.0)}}</td>
   <td>{{CompatGeckoDesktop(51)}}<sup>[1]</sup></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>39</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Android Webview</th>
   <th>Edge</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>39</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] Support for the <code>devicechange</code> event and for {{domxref("MediaDevices.ondevicechange")}} landed in Firefox 51, but <em>only for Mac</em>, and disabled by default. It can be enabled by setting the preference <code>media.ondevicechange.enabled</code> to <code>true</code>. Support for this event was added for Linux and Windows—and it was enabled by default—starting in Firefox 52.</p>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{domxref("MediaDevices.ondevicechange")}}</li>
</ul>