Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The fullScreen property of the Window interface indicates whether the window is displayed in full screen mode or not.


isInFullScreen = windowRef.fullScreen;

With chrome privileges, the property is read-write, otherwise it is read-only. Bear in mind that if you try to set this property without chrome privileges, it will not throw an exception and instead just silently fail. This is to prevent scripts designed to set this property in Internet Explorer from breaking.

Return value


A boolean. Possible Values:

  • true: The window is in full screen mode.
  • false: The window is not in full screen mode.


  • Switching between regular window and full screen will fire the "resize" event on the corresponding window.


if (window.fullScreen) {
  // it's fullscreen!
else {
  // not fullscreen!

Browser compatibility

BCD tables only load in the browser