---
title: MouseEvent.which
slug: Web/API/MouseEvent/which
tags:
  - API
  - 只读
  - 非标准
  - 鼠标事件
translation_of: Web/API/MouseEvent/which
---
<p>{{APIRef("DOM Events")}}</p>

<p>{{Non-standard_header}}</p>

<p>只读属性 <strong>MouseEvent.which</strong> 显示了鼠标事件是由哪个鼠标按键被按下所触发的。其他获得该信息的标准属性是 {{ domxref("MouseEvent.button") }} 与 {{ domxref("MouseEvent.buttons") }} 。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">var buttonPressed = instanceOfMouseEvent.which
</pre>

<h3 id="返回值">返回值</h3>

<p>表示一个特定按键的数字：</p>

<ul>
 <li><code>0</code>: 无</li>
 <li><code>1</code>: 左键</li>
 <li><code>2</code>: 中间滚轮（如果有的话）</li>
 <li><code>3</code>: 右键</li>
</ul>

<p>如果鼠标被设置为适用于左利手人士使用，那么引发的动作恰好相反。在这种情况下，该值应该从右往左看。</p>

<h2 id="规范">规范</h2>

<p>无规范定义该属性。</p>

<h2 id="Browser_compatibility" name="Browser_compatibility">浏览器兼容性</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Edge</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>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoDesktop(1)}}<sup>[1]</sup></td>
   <td>1.0</td>
   <td>9.0</td>
   <td>5.0</td>
   <td>1.0</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Edge</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Android</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{ CompatGeckoMobile(1) }} [1]</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] 在 {{event("mousemove")}} 事件对象上， <code>which</code> 属性被错误地设定为 <code>1</code> {{bug(1048294)}}.</p>

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

<ul>
 <li>{{ domxref("MouseEvent") }}</li>
</ul>