javascript如何自动关闭窗口

<script language="javascript">

<!--

function closewin()

{

self.opener=null;

self.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);

else closewin();

}

var i=10

clock();

//-->

</script>

<script language=javascript> 

<!-- 

this.window.opener = null; 

window.close(); 

//--> 

</script>