code: function (id, buttonState) {
      var changed;
      changed = this.handlePress(id, buttonState) |
                this.handleTouch(id, buttonState) |
                this.handleValue(id, buttonState);
      if (!changed) { return false; }
      this.el.emit(EVENTS.BUTTONCHANGED, this.buttonEventDetails[id], false);
      return true;
    }
docs: Handle presses and touches for a single button.
  
  @param {number} id - Index of button in Gamepad button array.
  @param {number} buttonState - Value of button state from 0 to 1.
  @returns {boolean} Whether button has changed in any way.