code: function () {
      var controllers = this.controllers;
      var gamepad;
      var gamepads;
      var i;
      var prevCount;
  
      gamepads = navigator.getGamepads && navigator.getGamepads();
      if (!gamepads) { return; }
  
      prevCount = controllers.length;
      controllers.length = 0;
      for (i = 0; i < gamepads.length; ++i) {
        gamepad = gamepads[i];
        if (gamepad && gamepad.pose) {
          controllers.push(gamepad);
        }
      }
  
      if (controllers.length !== prevCount) {
        this.el.emit('controllersupdated', undefined, false);
      }
    }
docs: Update controller list.