code: function (event) {
  
            var touchInvalid = false;
            if (event.touches !== undefined && event.touches.length > 1) {
              touchInvalid = true;
            } else if (event.originalEvent !== undefined &&
              event.originalEvent.touches !== undefined && event.originalEvent.touches.length > 1) {
              touchInvalid = true;
            }
            return touchInvalid;
          }
docs: Checks whether the touch is valid and multiple.
  
  @param event the event object.
  @returns {boolean} true if touch is multiple.