The hardwareUnitId read-only property of the VRDevice interface returns the distinct hardware ID for the overall hardware unit that this VRDevice is a part of. All devices that are part of the same physical piece of hardware will have the same hardwareUnitId.
The recommendedFieldOfView read-only property of the VREyeParameters interface describes the recommended field of view for the current eye — ideally based on user calibration.
The renderRect read-only property of the VREyeParameters interface specifies the viewport of a canvas into which visuals for the current eye should be rendered.
The hasOrientation read-only property of the VRPositionState interface returns a boolean indicating whether the VRPositionState.orientation property is valid (i.e. if the hardware is currently registering a valid orientation). If it is false, the orientation property will return null.