On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 1 on 2008-12-11
In Chrome Android version 18 on 2012-06-27
Not in Deno
In Edge version 12 on 2015-07-29
In Firefox version 1 on 2004-11-09 Note: Before version 62 this function returned null when called on a Window with no presentation (e.g. an iframe with display: none; set). Since 62 it returns a CSSStyleDeclaration object with length 0, containing empty strings (bug 1467722; also see bug 1471231 for further work).
In Firefox for Android version 4 on 2011-03-29 Note: Before version 62 this function returned null when called on a Window with no presentation (e.g. an iframe with display: none; set). Since 62 it returns a CSSStyleDeclaration object with length 0, containing empty strings (bug 1467722; also see bug 1471231 for further work).
In Internet Explorer version 9 on 2011-03-14
In Quest Browser version 5.0 on undefined
In Opera version 7.2 on 2003-09-23
In Opera Android version 10.1 on 2010-11-09
In Safari version 3 on 2007-10-26
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