Web/API/Window/unload event

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 StandardThe definition of 'unload' in that specification.	Living Standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	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 Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 4	Opera Full support 4	Safari Full support 3	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0

Legend

Full support: Full support

Web/API/Window/unload event

Contents

Examples

Specifications

Browser compatibility

Legend

See also