---
title: WheelEvent.deltaMode
slug: Web/API/WheelEvent/deltaMode
translation_of: Web/API/WheelEvent/deltaMode
---
<p>{{APIRef("DOM Events")}}</p>

<p><code><strong>WheelEvent.deltaMode</strong></code> 只读属性返回一个 <code>unsigned long</code> 类型的值, 声明 delta 的滚动值的单位. 可能的值为:</p>

<table class="standard-table">
 <tbody>
  <tr>
   <td class="header">Constant</td>
   <td class="header">Value</td>
   <td class="header">Description</td>
  </tr>
  <tr>
   <td><code>DOM_DELTA_PIXEL</code></td>
   <td><code>0x00</code></td>
   <td>delta 的值为 像素 级别.</td>
  </tr>
  <tr>
   <td><code>DOM_DELTA_LINE</code></td>
   <td><code>0x01</code></td>
   <td>delta 的值为 行 级别.</td>
  </tr>
  <tr>
   <td><code>DOM_DELTA_PAGE</code></td>
   <td><code>0x02</code></td>
   <td>delta 的值为 页 级别.</td>
  </tr>
 </tbody>
</table>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">var <code><em>unit</em> = <em>event</em>.deltaMode;</code></pre>

<h2 id="例子">例子</h2>

<pre class="brush: js">var syntheticEvent = new WheelEvent("syntheticWheel", {"deltaX": 4, "deltaMode": 0});

console.log(syntheticEvent.deltaMode);
</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('DOM3 Events','#widl-WheelEvent-deltaMode','WheelEvent.deltaMode')}}</td>
   <td>{{Spec2('DOM3 Events')}}</td>
   <td>Initial definition.</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>Edge</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>31</td>
   <td>{{ CompatVersionUnknown }}</td>
   <td>{{ CompatGeckoDesktop("17.0") }}</td>
   <td>{{ CompatIE("9.0") }}</td>
   <td>18</td>
   <td>7.0</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Edge</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{ CompatGeckoMobile("17.0") }}</td>
   <td>{{ CompatUnknown() }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatNo() }}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 class="note" id="另见">另见</h2>

<ul>
 <li>{{ event("wheel") }}</li>
 <li>{{domxref("WheelEvent")}}</li>
</ul>