Anyone knows to clear the contents of the window !!! in javascript

Hi,

<SCRIPT LANGUAGE='JavaScript'>
function clean()
{
document.clear();
}
</SCRIPT>
abcdefghijklmnopqrstuvwxyz
<INPUT TYPE="submit" value = 'submit' onclick='clean()'>

I am using the above code to clear the contents of the window
.. but on clicking the button i am unable to clear the content.

So if anybody knows how to clear the contents of the window, u can share it...

Thanks in advance,
Pradhip