The Fullscreen API provides an easy way for web content to be presented using the user's entire screen. The API lets you easily direct the browser to make an element and its children, if any, occupy the fullscreen, eliminating all browser user interface and other applications from the screen for the duration.
The Document.fullscreenElement read-only property returns the Element that is currently being presented in full-screen mode in this document, or null if full-screen mode is not currently in use.
The Document.fullscreenEnabled read-only property returns a Boolean that reports whether or not full-screen mode is available. Full screen mode is available only for a page that has no windowed plug-ins in any of its documents, and if all <iframe> elements which contain the document have their allowfullscreen attribute set.
The Document.onfullscreenchangeproperty is an event handler for the fullscreenchange event that is fire when a document goes in or out of the fullscreen mode.
The Document.onfullscreenerrorproperty is an event handler for the fullscreenchange event that is fire when a document goes that cannot go in fullscreen mode, even it has been requested.