让一竖线随着我的鼠标移动

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style>
#line{
position:absolute;
width:2px;
height:150px;
border-left:1px solid #333;
}
</style>
<script>
function move(e){
e = e || event;
var obj = document.getElementById("line");
obj.style.left = (e.clientX+10) + "px";
obj.style.top = (e.clientY+15) + "px";
}
document.onmousemove = move;
</script>
</head><body>    
<div id="line"></div>
</body>
</html>