JS手机端touch事件计算滑动距离的方法示例

function wetherScroll(){    var startX = startY = endX =endY =0;    var body=document.getElementsByTagName("body");    body.bind('touchstart',function(event){      var touch = event.targetTouches[0];      //滑动起点的坐标      startX = touch.pageX;      startY = touch.pageY;      // console.log("startX:"+startX+","+"startY:"+startY);    });    body.bind("touchmove",function(event){      var touch = event.targetTouches[0];      //手势滑动时，手势坐标不断变化，取最后一点的坐标为最终的终点坐标        endX = touch.pageX;        endY = touch.pageY;        // console.log("endX:"+endX+","+"endY:"+endY);    })    body.bind("touchend",function(event){      var distanceX=endX-startX,        distanceY=endY - startY;        // console.log("distanceX:"+distanceX+","+"distanceY:"+distanceY);        //移动端设备的屏幕宽度        var clientHeight; =document.documentElement.clientHeight;        // console.log(clientHeight;*0.2);        //判断是否滑动了，而不是屏幕上单击了        if(startY!=Math.abs(distanceY)){ //在滑动的距离超过屏幕高度的20%时，做某种操作          if(Math.abs(distanceY)>clientHeight*0.2){ //向下滑实行函数someAction1，向上滑实行函数someAction2          distanceY <0 ? someAction1():someAction2();        }        }        startX = startY = endX =endY =0;    })}