Accept only Number Value in TextBox

Hiii,

 I want to accept only Number i.e integer values in my textbox .

It only accepts numner not '.' or any letter in it.

have seen this on our forum :

It accepts both number and '.' also i want only numbers.

<script type="text/javascript">
        function onlyNumbersWithDot(e) {
            var charCode;
            if (e.keyCode > 0) {
                charCode = e.which || e.keyCode;
            }
            else if (typeof (e.charCode) != "undefined") {
                charCode = e.which || e.keyCode;
            }
            if (charCode == 46)
                return true
            if (charCode > 31 && (charCode < 48 || charCode > 57))
                return false;
            return true;         
        }
    </script>