On the standards track: Yes
Is Experimental: No
Is Deprecated: Yes
In Chrome version 1 on 2008-12-11
In Chrome Android version 18 on 2012-06-27
In Edge version 79 on 2020-01-15 Note: Only supported for KeyboardEvent and MouseEvent, not all UIEvent objects.
In Firefox version 1 on 2004-11-09 Note: On mousemove events, the which property is incorrectly always set to 1.
In Firefox for Android version 4 on 2011-03-29 Note: On mousemove events, the which property is incorrectly always set to 1.
In Internet Explorer version 9 on 2011-03-14 Note: Only supported for KeyboardEvent and MouseEvent, not all UIEvent objects.
In Quest Browser version 5.0 on undefined
In Opera version 15 on 2013-07-02 Note: Only supported for KeyboardEvent and MouseEvent, not all UIEvent objects.
In Opera Android version 14 on 2013-05-21 Note: Only supported for KeyboardEvent and MouseEvent, not all UIEvent objects.
In Safari version 1 on 2003-06-23
In Safari on iOS version 1 on 2007-06-29
In Samsung Internet version 1.0 on 2013-04-27
In WebView Android version 4.4 on 2013-12-09
In WebView on iOS version 1 on 2007-06-29