code: function(event) {
  
          /**
           * If connected gamepad has a **standard** layout:
           *
           * @see https://w3c.github.io/gamepad/#remapping about standard.
           */
          if (event.gamepad.mapping === 'standard') {
  
              this._standardGamepadIndex = event.gamepad.index;
              this._standardGamepadAvailable = true;
  
              this.onStandardGamepadReady(event.gamepad);
  
          }
  
      }
docs: Private methods: