<script type="text/javascript">
function onlyDigit(e) {
    var code = e.keyCode ? e.keyCode : e.charCode;
    if ( !( code ==  8   ||  // Backspace
            code ==  9   ||  // Tab
            code ==  33  ||  // PageUP
            code ==  34  ||  // PageDown
            code ==  35  ||  // End
            code ==  36  ||  // Home
            code ==  37  ||  // LeftArrow
            code ==  39  ||  // RightArrow
            code ==  45  ||  // Insert
            code ==  46  ||  // Delete
            ( code >=  48 ) && (code <=  57 ) ) )
    {
        if ( typeof(e.cancelBubble) != undefined ) {
            e.cancelBubble = true;
        }
        if ( typeof(e.stopPropagation) != 'undefined' ) {
            e.stopPropagation();
        }
        if ( e.cancelable ) {
            e.preventDefault();
        } 
        if ( typeof( e.returnValue ) != undefined ) {
            e.returnValue = false;
        }
        return false;
    }
}
</script>