Web platform features explorer

beforeunload

Limited availability
Tags: api

The beforeunload event is fired when the current window is about to be unloaded. Typically this is used to display a dialog to confirm if users really want to leave the page when there is unsaved data that would be lost.

Browser support

  • Chrome 1 Released on 2008-12-11
  • Chrome Android 18 Released on 2012-06-27
  • Edge 12 Released on 2015-07-29
  • Firefox 1 Released on 2004-11-09
  • Firefox for Android 4 Released on 2011-03-29
  • Safari 3 Released on 2007-10-26
  • Safari on iOS See webkit.org/b/219102

Baseline availability blocked since July 2015 by Safari on iOS (120 months)

Usage (according to Chrome Platform Status)

~57.270% of page loads. More data at chromestatus.