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Window: unload event - Web APIs 编辑

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

Bubbles	No
Cancelable	No
Interface	`Event`
Event handler property	`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, etc.)
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).

The unload event (and onunload event handler) are not the right features to use with sendBeacon. Instead for sendBeacon, use the visibilitychange and pagehide events. See discussion in the comments for the blog post Beacon API is broken.

Examples

<!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.

Specifications

Specification	Status	Comment
HTML Living Standard The definition of 'unload' in that specification.	Living Standard

Browser compatibility

BCD tables only load in the browser

Window: unload event - Web APIs 编辑

Examples

Specifications

Browser compatibility

See also

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Window: unload event - Web APIs 编辑

Examples

Specifications

Browser compatibility

See also

如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

词条统计

友情链接

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。