<html>
<head>
<title></title>
<script type="text/javascript">
function Validate(txt) {
txt.value = txt.value.replace(/[^, 0-9]+/g, '');
}
</script>
</head>
<body>
<form>
<input type = "text" id ="txt" onkeyup = "Validate(this)" />
</form>
</body>
</html>