The hardwareUnitId read-only property of the VRDisplay 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.

A DOMString containing the ID of the overall hardware unit.

The following snippet (see our VRDevice example) returns an array of all the VRDisplays connected to your computer via Navigator.getVRDisplays. For each connected device it then prints out the hardwareUnitId, VRDisplay.displayId, and VRDisplay.displayName.

var list = document.querySelector('ul');
var info = document.querySelector('p');
if(navigator.getVRDevices) {
  navigator.getVRDevices().then(function(myDevices) {
    reportDevices(myDevices);
  });
} else {
  info.textContent = 'WebVR API not supported by this browser.'
}

function reportDevices(devices) {
  for(i = 0; i < devices.length; i++) {
    var listItem = document.createElement('li');
    listItem.innerHTML = 'Device ' + (i+1)
                 + ': <strong>Hardware ID</strong>: ' + devices[i].hardwareUnitId
                 + ', <strong>VD Device ID</strong>: ' + devices[i].deviceId
                 + ', <strong>VR Device Name</strong>: ' + devices[i].deviceName
                 + '.';
    list.appendChild(listItem);
  }
}

This property was part of the old WebVR API that has been superseded by the WebXR Device API. It is no longer on track to becoming a standard.

Until all browsers have implemented the new WebXR APIs, it is recommended to rely on frameworks, like A-Frame, Babylon.js, or Three.js, or a polyfill, to develop WebXR applications that will work across all browsers [1].

• WebVR API homepage.
• https://mixedreality.mozilla.org/ — demos, downloads, and other resources from the Mozilla VR team.