function hitungmundur(div, detik, prefix, onComplete) {
    var target_date = new Date().getTime() + (detik * 1000);
    var days, hours, minutes, seconds;
    

    var interval = setInterval(function () {
        var current_date = new Date().getTime();
        var seconds_left = (target_date - current_date) / 1000;

        if (seconds_left <= 0) {
            clearInterval(interval);
            $('#' + div).html('');
            if (typeof onComplete === 'function') {
                onComplete();
            }
        } else {
            days = parseInt(seconds_left / 86400);
            seconds_left = seconds_left % 86400;

            hours = parseInt(seconds_left / 3600);
            seconds_left = seconds_left % 3600;

            minutes = parseInt(seconds_left / 60);
            seconds = parseInt(seconds_left % 60);

            var countdownString = '';
            if (days > 0) {
                countdownString += days + " hari ";
            }
            if (hours > 0) {
                countdownString += hours + " jam ";
            }
            if (minutes > 0) {
                countdownString += minutes + " menit ";
            }
            countdownString += seconds + " detik";

            $("#" + div).html(prefix + " " + countdownString);
        }
    }, 1000);
}