On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 33 on 2014-02-20
In Chrome Android version 33 on 2014-02-26
In Edge version 12 on 2015-07-29
In Firefox version 18 on 2013-01-08 Note: Since Firefox 56 it also returns true on macOS when the window is completely hidden by another non-translucent application.
In Firefox for Android version 18 on 2013-01-08 Note: Since Firefox for Android 56 it also returns true on macOS when the window is completely hidden by another non-translucent application.
In Internet Explorer version 10 on 2012-10-26
In Quest Browser version 5.0 on undefined
In Opera version 12.1 on 2012-11-20
In Opera Android version 12.1 on 2012-10-09
In Safari version 7 on 2013-10-22
In Safari on iOS version 7 on 2013-09-18
In Samsung Internet version 2.0 on 2014-10-17
In WebView Android version 4.4.3 on 2014-06-02
In WebView on iOS version 7 on 2013-09-18