---
title: 'Window: blur event'
slug: Web/API/Window/blur_event
translation_of: Web/API/Window/blur_event
---
<div>{{APIRef}}</div>

<p>当元素失去焦点时，<strong><code>blur</code></strong>事件将触发。</p>

<p>与 <code>blur</code> 相反的是{{domxref("Window/focus_event", "focus")}}。</p>

<table class="properties">
 <tbody>
  <tr>
   <th scope="row">Bubbles（是否支持冒泡）</th>
   <td>No</td>
  </tr>
  <tr>
   <th scope="row">Cancelable（可撤销）</th>
   <td>No</td>
  </tr>
  <tr>
   <th scope="row">Interface（接口）</th>
   <td>{{DOMxRef("FocusEvent")}}</td>
  </tr>
  <tr>
   <th scope="row">Event handler property（事件处理程序属性）</th>
   <td>{{domxref("GlobalEventHandlers/onblur", "onblur")}}</td>
  </tr>
  <tr>
   <th scope="row">Sync / Async（同步/异步）</th>
   <td>Sync</td>
  </tr>
  <tr>
   <th scope="row">Composed</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>此示例当文档失去焦点时，更改其外观。它使用{{domxref("EventTarget.addEventListener()","addEventListener()")}} 去监听{{domxref("Window/focus_event", "focus")}}和 <code>blur</code> 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("在线示例")}}</p>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName("UI Events", "#event-type-blur")}}</td>
   <td>{{Spec2("UI Events")}}</td>
   <td>Added info that this event is composed.</td>
  </tr>
  <tr>
   <td>{{SpecName("DOM3 Events", "#event-type-blur")}}</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>{{Compat("api.Window.blur_event")}}</p>

<p>{{DOMxRef(" document. activeelement ")}}的值在处理({{bug(452307)}})时因浏览器而异 ;({{bug(452307)}}):IE10将其设置为焦点将移动到的元素，而Firefox和Chrome通常将其设置为文档的 body。</p>

<h2 id="参见">参见</h2>

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