CheckForInt

function CheckForInt(e) {
    var charCode
    if (window.event) // IE
    {
        charCode = event.keyCode; //e.keyCode;
    }
    else if (e.which) // Netscape/Firefox/Opera
    {
        charCode = e.which;
    }
    //var charCode = ( event.which ) ? event.which : event.keyCode;
    return (charCode >= 48 && charCode <= 57);
}