jq div拖动（移动端和pc端）

HTML：

<div style="width: 100px; height: 100px; background-color: darkgray; position:absolute;left: 0px; top: 0px;" id="barrage">div>

js:

/*拖动事件*/
    var cont=$("#barrage");    
    var contW=$("#barrage").width();
    var contH=$("#barrage").height();          
    var startX,startY,sX,sY,moveX,moveY, disX, disY;        
    var winW=$(window).width();    
    var winH=$(window).height();
    cont.on({//绑定事件
        touchstart:function(e){             
            startX = e.originalEvent.targetTouches[0].pageX;    //获取点击点的X坐标 
            startY = e.originalEvent.targetTouches[0].pageY;    //获取点击点的Y坐标
            //console.log("startX="+startX+"************startY="+startY);
            sX=$(this).offset().left;//相对于当前窗口X轴的偏移量
            sY=$(this).offset().top;//相对于当前窗口Y轴的偏移量
            //console.log("sX="+sX+"***************sY="+sY);
            leftX=startX-sX;//鼠标所能移动的最左端是当前鼠标距div左边距的位置
            rightX=winW-contW+leftX;//鼠标所能移动的最右端是当前窗口距离减去鼠标距div最右端位置
            topY=startY-sY;//鼠标所能移动最上端是当前鼠标距div上边距的位置
            bottomY=winH-contH+topY;//鼠标所能移动最下端是当前窗口距离减去鼠标距div最下端位置             
            },
        touchmove:function(e){              
            e.preventDefault();
            moveX=e.originalEvent.targetTouches[0].pageX;//移动过程中X轴的坐标
            moveY=e.originalEvent.targetTouches[0].pageY;//移动过程中Y轴的坐标
            //console.log("moveX="+moveX+"************moveY="+moveY);
            if(moveXif(moveX>rightX){moveX=rightX;}
            if(moveYif(moveY>bottomY){moveY=bottomY;}
            $(this).css({
                "left":moveX+sX-startX,
                "top":moveY+sY-startY,                  
            });
        },
        mousedown: function(ev){
            var patch = parseInt($(this).css("height"))/2;
            //console.log(patch);
            $(this).mousemove(function(ev){
                var oEvent = ev || event;
                //console.log(oEvent.target);
                var oX = oEvent.clientX;
                var oY = oEvent.clientY;
                var t = oY - patch;
                var l = oX - patch;
                var w = $(window).width() - $(this).width();
                var h = $(window).height() - $(this).height();
                if(t<0){t = 0}
                if(l<0){l=0}
                if(t>h){t=h}
                if(l>w){l=w}
                $(this).css({top:t,left:l})
            });
            $(this).mouseup(function(){
                $(this).unbind('mousemove');
            });
        }
    });

另附一种pc端原生js的写法：

 window.onload = function () {
            var oDiv = document.getElementById('oDiv');
            var disX = 0, disY = 0;
            oDiv.onmousedown = function (ev) {
                var oEvent = ev || event;
                disX = oEvent.clientX - oDiv.offsetLeft;
                disY = oEvent.clientY - oDiv.offsetTop;
                document.onmousemove = function (ev) {
                    var oEvent = ev || event;
                    var l = oEvent.clientX - disX;
                    var t = oEvent.clientY - disY;
                    console.log(l);
                    if(l <= 0){ l = 0}
                    if(t < 0){t = 0}
                    if(l > document.documentElement.clientWidth - oDiv.offsetWidth){
                        l = document.documentElement.clientWidth - oDiv.offsetWidth;
                    }
                    if(t > document.documentElement.clientHeight - oDiv.offsetHeight){
                        t = document.documentElement.clientHeight - oDiv.offsetHeight;
                    }
                    oDiv.style.left = l + 'px';
                    oDiv.style.top = t + 'px';

                }

                document.onmouseup = function (ev) {
                    document.onmousemove = null;
                    document.onmouseup = null;
                }

            }
        }