code: function () {
      var data = this.data;
      var controllerIndex = data.hand === 'right' ? 0 : data.hand === 'left' ? 1 : 2;
      checkControllerPresentAndSetup(this, GAMEPAD_ID_PREFIX, {index: controllerIndex});
    }
docs: Once OpenVR returns correct hand data in supporting browsers, we can use hand property.
  var isPresent = checkControllerPresentAndSetup(this.el.sceneEl, GAMEPAD_ID_PREFIX,
  { hand: data.hand });
  Until then, use hardcoded index.