Number of invoices: 0<br/><script src="/js/jquery.min.jsm.js"></script>

<script type="text/javascript">
            function sync (id_invoice) {
                $.ajax({
                  url:"sync.php?id="+id_invoice, //the page containing php script
                  type: "GET", //request type
                  success:function(result){
                   alert(result);
                 }
               });
            }
        </script>