files/zh-cn/web/api/window/focus_event/index.html


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---
title: 'Window: focus event'
slug: Web/API/Window/focus_event
tags:
  - API
  - Event
  - Focus
translation_of: Web/API/Window/focus_event
---
<div>{{APIRef}}</div>

<p>当元素获得焦点时， <strong><code>focus</code></strong> 事件就会触发。</p>

<p>与 <code>focus</code> 相反的事件是 {{domxref("Window/blur_event", "blur")}}</p>

<table class="properties">
 <tbody>
  <tr>
  </tr>
  <tr>
   <th>Bubbles（支持冒泡）</th>
   <td>No</td>
  </tr>
  <tr>
   <th>Cancelable（可撤销）</th>
   <td>No</td>
  </tr>
  <tr>
   <th>Interface（接口）</th>
   <td>{{DOMxRef("FocusEvent")}}</td>
  </tr>
  <tr>
   <th>Event handler property（事件处理程序属性）</th>
   <td>{{domxref("GlobalEventHandlers/onfocus", "onfocus")}}</td>
  </tr>
  <tr>
   <th>Sync / Async（同步/异步）</th>
   <td>Sync</td>
  </tr>
  <tr>
   <th>Composed（可组成）</th>
   <td>Yes</td>
  </tr>
 </tbody>
</table>

<h2 id="示例">示例</h2>

<h3 id="在线示例">在线示例</h3>

<p>本示例在失去焦点时更改文档的外观。它使用 {{domxref("EventTarget.addEventListener()", "addEventListener()")}} 监听 <code>focus</code> 和 {{domxref("Window/blur_event", "blur")}} 事件。</p>

<h4 id="HTML">HTML</h4>

<pre class="brush: html">&lt;p id="log"&gt;Click on this document to give it focus.&lt;/p&gt;</pre>

<h4 id="CSS">CSS</h4>

<pre class="brush: css">.paused {
  background: #ddd;
  color: #555;
}</pre>

<h4 id="JavaScript">JavaScript</h4>

<pre class="brush: js">function pause() {
  document.body.classList.add('paused');
  log.textContent = 'FOCUS LOST!';
}

function play() {
  document.body.classList.remove('paused');
  log.textContent = 'This document has focus. Click outside the document to lose focus.';
}

const log = document.getElementById('log');

window.addEventListener('blur', pause);
window.addEventListener('focus', play);</pre>

<h4 id="结果">结果</h4>

<p>{{EmbedLiveSample("Live_example")}}</p>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">规范</th>
   <th scope="col">状态</th>
   <th scope="col">备注</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName("UI Events", "#event-type-focus")}}</td>
   <td>{{Spec2("UI Events")}}</td>
   <td>添加了组成此事件的信息。</td>
  </tr>
  <tr>
   <td>{{SpecName("DOM3 Events", "#event-type-focus")}}</td>
   <td>{{Spec2("DOM3 Events")}}</td>
   <td>初始定义</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{Compat("api.Window.focus_event")}}</p>

<h2 id="参考">参考</h2>

<ul>
 <li>相关联事件： {{domxref("Window/blur_event", "blur")}}</li>
 <li><code>Element</code> 目标上的这个事件: {{domxref("Element/focus_event", "focus")}} 事件</li>
</ul>