code: function evtTouchMove(event) {
          if (event.touches.length > 1) {
              cancelTouch();
          } else {
              var touch = event.touches[0];
  
              touchDX = touch.pageX - touchStartX;
              touchDY = touch.pageY - touchStartY;
          }
          try {
              event.preventDefault();
          } catch (err) {
              console.log(err);
          }
      }
docs: touch事件