WindowEventHandlers.onunload
The onunload property of the
WindowEventHandlers mixin is the event handler for
processing unload events. These events fire when the window is unloading
its content and resources. The resource removal is processed after the
unload event occurs.
Note: Browsers equipped with pop-up blockers will ignore all
Window.open() method calls in onunload event handler
functions.
Warning: The onunload (and the
unload event
itself) are not the right features to use with
sendBeacon().
Instead for
sendBeacon(), use
the
visibilitychange and
pagehide events.
See discussion comments in the blog post Beacon API is
broken.
Syntax
window.addEventListener("unload", function(event) { /* ... */ });
window.onunload = function(event) { /* ... */ };
Typically, it is better to use window.addEventListener() and the unload event, instead of
onunload.
Specifications
| Specification |
|---|
| HTML Standard # handler-window-onunload |
Browser compatibility
BCD tables only load in the browser
In Firefox 1.5, using this event handler in your page prevents the browser from caching the page in the in-memory bfcache. See Using Firefox 1.5 caching for details.