Fullscreen

Tells you the Element that's currently being displayed in fullscreen mode on the DOM (or shadow DOM). If this is Maybe::Nothing, the document (or shadow DOM) is not in fullscreen mode.

Issues an asynchronous request to make the element be displayed in fullscreen mode.

It's not guaranteed that the element will be put into full screen mode. If permission to enter full screen mode is granted, the returned Promise will resolve and the element will receive a fullscreenchange event to let it know that it's now in full screen mode. If permission is denied, the promise is rejected and the element receives a fullscreenerror event instead. If the element has been detached from the original document, then the document receives these events instead.

Requests that the element on this document which is currently being presented in fullscreen mode be taken out of fullscreen mode, restoring the previous state of the screen. This usually reverses the effects of a previous call to Fullscreen.enter.

Tells you whether or not fullscreen mode is currently activated

Tells you whether or not it is possible to engage fullscreen mode. This is false if fullscreen mode is not available for any reason (such as the "fullscreen" feature not being allowed, or fullscreen mode not being supported).