The activeVRDisplays read-only property of the Navigator interface returns an array containing every VRDisplay object that is currently presenting (VRDisplay.ispresenting is true).
The getVRDisplays() method of the Navigator interface returns a promise that resolves to an array of VRDisplay objects representing any available VR devices connected to the computer.
The NavigatorConcurrentHardwaremixin adds to the Navigator interface features which allow Web content to determine how many logical processors the user has available, in order to let content and Web apps optimize their operations to best take advantage of the user's CPU.