<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
#div1 {
width: 200px;
height: 200px;
background-color: #0F0;
position: absolute
}
</style>
<script>
window.onload = function() {
document.onmousemove = function(ev) {
var oEvent = ev || event;
var oDiv = document.getElementById("div1");
var aaa = document.documentElement.scrollTop || document.body.scrollTop;
oDiv.style.left = oEvent.clientX + "px";
oDiv.style.top = oEvent.clientY + "px";
}
}
</script>
</head>
<body style="height:2000px">
<div id="div1"></div>
</body>
</html>
原文：http://www.cnblogs.com/cxy66/p/6050373.html