Prova questo....
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Untitled</title>
<script language="JavaScript" type="text/javascript">
<!--
function ltrim(item) {
return item.replace(/^\s*/gi,"");
}
function rtrim(item) {
return item.replace(/\s*$/gi,"");
}
function trim(item) {
return rtrim(ltrim(item));
}
function controlla(aValue) {
aValue = trim(aValue);
pattern = /^mms:[/][/]\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\:\d{4}$/;
if (! aValue.match(pattern)) {
alert("falso");
return false;
} // if (! aValue.match(pattern))
alert("ok");
return true;
} // function controlla(aValue)
//-->
</script>
</head>
<body>
<input type="text" id="testo" size="25">
<input type="button" value="Controlla" onclick="controlla(document.getElementById('testo').value)">
</body>
</html>