---
title: GlobalEventHandlers.onselectstart
slug: Web/API/GlobalEventHandlers/onselectstart
translation_of: Web/API/GlobalEventHandlers/onselectstart
---
<div>{{ApiRef('DOM')}}{{SeeCompatTable}}</div>

<p><code><strong>GlobalEventHandlers.onselectstart</strong></code> 表示 {{event("selectstart")}} 事件绑定的事件处理器，比如用户在网页上开始选择任意文本内容时触发。</p>

<p><em>译者注：在输入控件中选择文本时，触发的是控件绑定的 {{event("select")}} 事件。</em></p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox"><em>obj</em>.onselectstart = <em>function</em>;
</pre>

<h2 id="Example">Example</h2>

<pre class="brush: html">document.onselectstart = function() {
  console.log("Selection started!");
};
</pre>

<p>详细用法参见 <a href="https://github.com/chrisdavidmills/selection-api-examples/#key-quote-generator-see-it-running-live">Key quote generator</a> 示例。</p>

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

<table class="spectable standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Selection API','#dom-globaleventhandlers-onselectstart','GlobalEventHandlers.onselectstart')}}</td>
   <td>{{Spec2('Selection API')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox (Gecko)</th>
   <th>Chrome</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatGeckoDesktop(43)}}<sup>[1]</sup><br>
    {{CompatGeckoDesktop(52)}}<sup>[2]</sup></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>1.3</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Android</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td><code>onselectionchange</code></td>
   <td>{{CompatGeckoMobile(43)}}<sup>[1]</sup><br>
    {{CompatGeckoMobile(52)}}<sup>[2]</sup></td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] This is implemented behind the <code>dom.select_events.enabled</code> preference, which defaults to <code>false</code> except on Nightly.</p>

<p>[2] This is now fully enabled on Firefox 52 release version.</p>

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

<ul>
 <li>{{event("selectstart")}}</li>
 <li>{{domxref("GlobalEventHandlers.onselectionchange")}}</li>
</ul>