div可随意拖动

   function DragDlg(){
      var helperdialogwrapper =$(".helper-dialog-wrapper");
        var x = 0;
        var y = 0;
        var l = 0;
        var t = 0;
        var isDown = false;
        //鼠标按下事件
        $(".helper-dialog-wrapper").bind("mousedown",function(e) {
            //获取x坐标和y坐标
            x = e.clientX;
            y = e.clientY;

            //获取左部和顶部的偏移量
            l = helperdialogwrapper.offset().left;
            t = helperdialogwrapper.offset().top;
            //开关打开
            isDown = true;
            //设置样式  
        });
        //鼠标移动
        window.onmousemove = function(e) {
            if (isDown == false) {
                return;
            }
            //获取x和y
            var nx = e.clientX;
            var ny = e.clientY;
            //计算移动后的左偏移量和顶部的偏移量
            var nl = parseInt(l)+(parseInt(nx) -parseInt(x));
            var nt = parseInt(t)+(parseInt(ny) -parseInt(y));
            sss=parseInt(nx) -parseInt(x);
            lll=parseInt(ny) -parseInt(y);
//这里设置offset而不是css，因为获取时是根据offset获取的偏移量
            $(".helper-dialog-wrapper").offset({top:nt,left:nl});
        }
        //鼠标抬起事件
        $(".helper-dialog-wrapper").bind("mouseup",function() {
            //开关关闭
            isDown = false;
        }
        );
    }