code: function createMouseEvent(eventName, originalEvent, finger) {
      var e = document.createEvent('MouseEvent');
  
      e.initMouseEvent(eventName, true, true,
        originalEvent.view, originalEvent.detail,
        finger.x || originalEvent.screenX, finger.y || originalEvent.screenY,
        finger.x || originalEvent.clientX, finger.y || originalEvent.clientY,
        originalEvent.ctrlKey, originalEvent.shiftKey,
        originalEvent.altKey, originalEvent.metaKey,
        originalEvent.button, finger.target || originalEvent.relatedTarget
      );
  
      e.synthetic = true;
  
      // Set this so we can match shared targets later.
      e._finger = finger;
  
      return e;
    }
docs: Create a synthetic event from a real event and a finger.