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.
The MediaStream.onaddtrack property is an EventHandler which specifies a function to be called when the addtrack event occurs on a MediaStream instance. This happens when a new track of any kind is added to the media stream. This event is fired when the browser adds a track to the stream (such as when a RTCPeerConnection is renegotiated or a stream being captured using HTMLMediaElement.captureStream() gets a new set of tracks because the media element being captured loaded a new source.
The MediaStream.onremovetrack property is an EventHandler which specifies a function to be called when the removetrack event occurs on a MediaStream instance. This happens when a track of any kind is removed from the media stream. This event is fired when the browser removes a track from the stream (such as when a RTCPeerConnection is renegotiated or a stream being captured using HTMLMediaElement.captureStream() gets a new set of tracks because the media element being captured loaded a new source.
The MediaStreamTrack.onended event handler is used to specify a function which serves as an EventHandler to be called when the ended event occurs on the track. This event occurs when the track will no longer provide data to the stream for any reason, including the end of the media input being reached, the user revoking needed permissions, the source device being removed, or the remote peer ending a connection.
The MediaStreamTrack.onunmute event handler is a property called when the unmute event is received. Such an event is sent when the track is again able to send data.