code: function onMouse(touchType) {
    return function(ev) {
      // prevent mouse events
  
      if (ev.which !== 1) {
        return;
      }
  
      // The EventTarget on which the touch point started when it was first placed on the surface,
      // even if the touch point has since moved outside the interactive area of that element.
      // also, when the target doesnt exist anymore, we update it
      if (ev.type === 'mousedown' || !eventTarget || eventTarget && !eventTarget.dispatchEvent) {
        eventTarget = ev.target;
      }
  
      triggerTouch(touchType, ev);
  
      // reset
      if (ev.type === 'mouseup') {
        eventTarget = null;
      }
    };
  }
docs: only trigger touches when the left mousebutton has been pressed
  @param touchType
  @returns {Function}