Anyone can comment this out?

[Vizuke]

Can anyone comment this peice of coding out for me? I got it from w3schools.com. Thanks.


<script type="text/css">

function noNumbers(e) {
var keynum
var keychar
var numcheck
if(window.event) {
keynum = e.keyCode
}
else if(e.which) {
keynum = e.which
}
keychar = String.fromCharCode(keynum)
numcheck = /\d/
return !numcheck.test(keychar)
}

</script>