function jam_jalan(id_nya){
            var stopwatch = setInterval(function(){
                angka++;
                var jam = angka.toString();
                $('#demo2').text(jam.toHHMMSS());
            },1000);
            return stopwatch;
        }

        String.prototype.toHHMMSS = function () {
            var sec_num = parseInt(this, 10); // don't forget the second param
            var hours   = Math.floor(sec_num / 3600);
            var minutes = Math.floor((sec_num - (hours * 3600)) / 60);
            var seconds = sec_num - (hours * 3600) - (minutes * 60);

            if (hours   < 10) {hours   = "0"+hours;}
            if (minutes < 10) {minutes = "0"+minutes;}
            if (seconds < 10) {seconds = "0"+seconds;}
            return hours+':'+minutes+':'+seconds;
        }