zepto判断左右滑动

<script>
var startPosition, endPosition, deltaX, deltaY, moveLength;
$(".content").bind('touchstart', function(e) {
  var touch = e.touches[0];
  startPosition = {
    x: touch.pageX,
    y: touch.pageY
  }
}).bind('touchmove', function(e) {
  var touch = e.touches[0];
  endPosition = {
    x: touch.pageX,
    y: touch.pageY
  };
  
  deltaX = endPosition.x - startPosition.x;
  deltaY = endPosition.y - startPosition.y;
  moveLength = Math.sqrt(Math.pow(Math.abs(deltaX), 2) + Math.pow(Math.abs(deltaY), 2));
}).bind('touchend', function(e) {
  if (deltaX < 0) { // 向左划动
    console.log("向左划动");
  } else if (deltaX > 0) { // 向右划动
    console.log("向右划动");
  }
});
</script>