esempiuzzo

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<script language="javascript">
function controlla(){
string = document.pippo.testo.value;
aa = string.match(/[a-z][A-Z]/gi);
if (aa){
alert("attenzione solo numeri");
}
else {
alert("ok funziona");
}
}
</script>
</HEAD>
<BODY>
<form name="pippo" method="get" action="prova.html">
<input type="text" name="testo">
<input type="button" onclick="javascript:controlla()" value="prova">
</form>
</BODY>
</HTML>