<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
        <script type="text/javascript">
            function _comma(number) {
               let str = number.toString();
                return  str.replace(/(\d)(?=(?:\d{3})+$)/g, '$1,');
            }
        </script>
    </body>
</html>