Js 定时关闭窗口

<script language="javascript">
function closewin(){
window.opener=null; //for Ie6
window.open("","_self"); //for ie7-8
window.close();
}

function clock(){
i=i-1;
document.title="本窗口将在"+i+"秒后自动关闭！";
if(i>0){
setTimeout("clock();",1000); //以毫秒为单位的.1000代表一秒钟.根据你需要修改这个时间.
}
else{
closewin();
}
}

var i=2;
clock();
</script>