The MediaTrackSupportedConstraints dictionary establishes the list of constrainable properties
recognized by the user agent or browser in its implementation of the MediaStreamTrack object.
An object conforming to MediaTrackSupportedConstraints is returned by
MediaDevices.getSupportedConstraints().
The MediaTrackSupportedConstraints dictionary establishes the list of constrainable properties recognized by the user agent or browser in its implementation of the MediaStreamTrack object. An object conforming to MediaTrackSupportedConstraints is returned by MediaDevices.getSupportedConstraints().
MDN