实例2： 跟随鼠标的DIV--
<script>
document.onmousemove=function (ev)
{
var oEvent=ev||event;
var oDiv=document.getElementById('div1');
var scrollTop=document.documentElement.scrollTop||document.body.scrollTop;
var scrollLeft=document.documentElement.scrollLeft||document.body.scrollLeft;
oDiv.style.left=oEvent.clientX+scrollLeft+'px';
oDiv.style.top=oEvent.clientY+scrollTop+'px'; //一般都要这么写，防止潜在的问题发生。oEvent.clientY+scrollTop
//非谷歌浏览器情况下document.documentElement.scrollTop；谷歌浏览器情况下document.body.scrollTop;
};
</script>
实例3：offsetLeft
<head>
<style>
#div1 {100px; height:100px; background:red; border:1px solid black; padding:10px; margin:20px; position:absolute; left:100px; top:100px;}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
window.onload=function ()
{
var oDiv=document.getElementById('div1');
alert(oDiv.offsetLeft);
};
</script>
</head>
<body>
<div id="div1"></div>
</body>