<html>
<body>
<script type="text/javascript">
function noNumbers(e)
{
var keynum
var keychar
var numcheck
if(window.event) // IE
keynum = e.keyCode
}
else if(e.which) // Netscape/Firefox/Opera
keynum = e.which
keychar = String.fromCharCode(keynum)
numcheck = /\d/
return !numcheck.test(keychar)
</script>
<form>
Type some text (numbers not allowed):
<input type="text" onkeydown="return noNumbers(event)" />
</form>
</html>