Window: unload event

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unload event is fired when the document or a child resource is being unloaded.

冒泡	No
可取消	No
接口	`事件`
事件处理程序特性	`onunload`

It is fired after:

beforeunload (cancelable event)
pagehide

The document is in the following state:

All the resources still exist (img, iframe etc.)
Nothing is visible anymore to the end user
UI interactions are ineffective ( window.open , alert , confirm ，等)
An error won't stop the unloading workflow

Please note that the unload event also follows the document tree: parent frame unload will happen before child frame unload (see example below).

范例

<!DOCTYPE html>
<html>
  <head>
    <title>Parent Frame</title>
    <script>
      window.addEventListener('beforeunload', function(event) {
        console.log('I am the 1st one.');
      });
      window.addEventListener('unload', function(event) {
        console.log('I am the 3rd one.');
      });
    </script>
  </head>
  <body>
    <iframe src="child-frame.html"></iframe>
  </body>
</html>

Below, the content of child-frame.html :

<!DOCTYPE html>
<html>
  <head>
    <title>Child Frame</title>
    <script>
      window.addEventListener('beforeunload', function(event) {
        console.log('I am the 2nd one.');
      });
      window.addEventListener('unload', function(event) {
        console.log('I am the 4th and last one…');
      });
    </script>
  </head>
  <body>
      ☻
  </body>
</html>

When the parent frame is unloaded, events will be fired in the order described by the console.log() messages.

规范

规范	状态	注释
UI Events The definition of 'unload' in that specification.	工作草案

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`unload` event	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 3	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0

图例

完整支持

另请参阅

相关事件： DOMContentLoaded , readystatechange , load
Unloading Documents — unload a document

元数据

最后修改： Jun 6, 2019

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图例

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