var flag = false;    var cur = {        x:0,        y:0    }    var nx,ny,dx,dy,x,y ;    function down(){        flag = true;        var touch ;        if(event.touches){            touch = event.touches[0];        }else {            touch = event;        }        cur.x = touch.clientX;        cur.y = touch.clientY;        dx = div2.offsetLeft;        dy = div2.offsetTop;    }    function move(){        if(flag){            var touch ;            if(event.touches){                touch = event.touches[0];            }else {                touch = event;            }            nx = touch.clientX - cur.x;            ny = touch.clientY - cur.y;            x = dx+nx;            y = dy+ny;            div2.style.left = x+"px";            div2.style.top = y +"px";            //阻止页面的滑动默认事件            document.addEventListener("touchmove",function(){                event.preventDefault();            },false);        }    }    var div2 = document.getElementById("div2");    div2.addEventListener("mousedown",function(){        down();    },false);    div2.addEventListener("touchstart",function(){        down();    },false)    div2.addEventListener("mousemove",function(){        move();    },false);    div2.addEventListener("touchmove",function(){        move();    },false)    document.body.addEventListener("mouseup",function(){        flag = false;    },false);    div2.addEventListener("touchend",function(){        flag = false;    },false)