<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        div{
            height: 5px;
            width: 5px;
            background: red;
            position: absolute;

        }
    </style>
    <script>
        function getPos (ev)
        {
            var scrollTop = document.documentElement.srollTop||document.body.scrollTop;
            var scrollLeft = document.documentElement.scrollLeft||document.body.scrollLeft;
            return{x:ev.clientX+scrollLeft+'px',y:ev.clientY+scrollTop+'px'}

        }
        document.onmousemove = function (ev){
            var oDiv = document.getElementsByTagName('div');
            var oEvent = ev||event;

            for(var i=oDiv.length-1;i>0;i--)
            {
                oDiv[i].style.left = oDiv[i-1].offsetLeft+'px';
                oDiv[i].style.top = oDiv[i-1].offsetTop+'px';
            }
            oDiv[0].style.left = getPos(oEvent).x;
            oDiv[0].style.top = getPos(oEvent).y;
        };

    </script>
</head>
<body>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
</body>
</html>

有点小疑问，不知道oDiv[0]为什么放在for循环前后都没有问题。求指导！！