鼠标移动，box1跟着移动
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
body {
height: 2000px;
width: 2000px;
}
#box1 {
width: 100px;
height: 100px;
background-color: red;
/*开启绝对定位*/
position: absolute;
}
</style>
</head>
<body>
<div id="box1"></div>
</body>
<script>
//绑定鼠标移动事件
document.onmousemove = function(event) {
//获取box1
var box1 = document.getElementById("box1");
//解决兼容问题
event = event || window.event;
//获取滚动条滚动的距离
//chrome认为浏览器的滚动条是body的，可以通过body.scrollTop来获取
//火狐等浏览器认为浏览器的滚动条是html的，
var st = document.body.scrollTop || document.documentElement.scrollTop;
var sl = document.body.scrollLeft || document.documentElement.scrollLeft;
//获取鼠标在当前的可见窗口的坐标
var left = event.clientX;
var top = event.clientY;
//pageX和pageY可以获取鼠标相对于当前页面的坐标
/*var left=event.pageX;
var top=event.pageY;*/
//设置div的偏移量
box1.style.left = left + sl + "px";
box1.style.top = top + st + "px";
};
</script>
</html>
