---
title: 'Document: scroll event'
slug: Web/API/Document/scroll_event
tags:
  - API
  - DOM
  - Event
  - Reference
  - Scroll
  - requestAnimationFram
  - 事件
  - 参考
  - 滚动
translation_of: Web/API/Document/scroll_event
---
<p>文档视图或者一个元素在滚动时，会触发元素的<strong><code>scroll</code></strong>事件。</p>

<table class="properties">
 <thead>
 </thead>
 <tbody>
  <tr>
   <th>Bubbles</th>
   <td>Yes</td>
  </tr>
  <tr>
   <th>Cancelable</th>
   <td>No</td>
  </tr>
  <tr>
   <th>Interface</th>
   <td>{{DOMxRef("Event")}}</td>
  </tr>
  <tr>
   <th>Event handler property</th>
   <td>{{DOMxRef("GlobalEventHandlers.onscroll", "onscroll")}}</td>
  </tr>
 </tbody>
</table>

<div class="blockIndicator note">
<p><strong>注意：</strong>在 iOS UIWebViews中， 滚动进行时不会触发 <code>scroll</code> 事件；只有当滚动结束后事件才会被触发。参见 <a href="https://github.com/twbs/bootstrap/issues/16202">Bootstrap issue #16202</a>。Safari 和 WKWebViews 则没有这个问题。</p>
</div>

<h2 id="示例">示例</h2>

<h3 id="Scroll_事件节流">Scroll 事件节流</h3>

<p>由于 <code>scroll</code> 事件可被高频触发，事件处理程序不应该执行高性能消耗的操作，如DOM操作。而更推荐的做法是使用 {{DOMxRef("Window.requestAnimationFrame()", "requestAnimationFrame()")}}, {{DOMxRef("WindowOrWorkerGlobalScope.setTimeout()", "setTimeout()")}} 或 {{DOMxRef("CustomEvent")}} 给事件节流，如下所述。</p>

<p>然而需要注意的是，输入事件和动画帧常常以差不多的频率被触发，因此以下优化常常不必要。这个例子使用 <code>requestAnimationFrame</code> 优化 <code>scroll</code> 事件。</p>

<pre class="brush: js">// 参见: http://www.html5rocks.com/en/tutorials/speed/animations/

let last_known_scroll_position = 0;
let ticking = false;

function doSomething(scroll_pos) {
  // 根据滚动位置做的事
}

window.addEventListener('scroll', function(e) {
  last_known_scroll_position = window.scrollY;

  if (!ticking) {
    window.requestAnimationFrame(function() {
      doSomething(last_known_scroll_position);
      ticking = false;
    });

    ticking = true;
  }
});</pre>

<p>在 <code><a href="/en-US/docs/Web/API/Document/defaultView/resize_event">resize</a></code> 事件页面中查看更多类似的例子。</p>

<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>
  </tr>
  <tr>
   <td>{{SpecName('DOM3 Events', '#event-type-scroll')}}</td>
   <td>{{Spec2('DOM3 Events')}}</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{Compat("api.Document.scroll_event")}}</p>

<h2 id="参见">参见</h2>

<ul>
 <li><a href="/en-US/docs/Web/API/Element/scroll_event">Element: <code>scroll</code> event</a></li>
</ul>