// Set the date we're counting down to
        const duration =  seconds_left;
        var countDownDate = new Date().getTime() + duration  * 1000;

        var x = setInterval(function() {
        var now = new Date().getTime();

        var distance = countDownDate - now;

        // Time calculations for hours, minutes and seconds
        var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
        var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
        var seconds = Math.floor((distance % (1000 * 60)) / 1000);
            if(document.getElementById("time") !== null && hours < 1 ){
                document.getElementById("time").innerHTML =  minutes + ":" + ((seconds < 10) ? "0" + seconds : seconds); //if seconds is lower then 10 add a 0 else just show seconds
            }else if(hours >= 1){
                document.getElementById("time").innerHTML = hours + ":" + minutes + ":" + ((seconds < 10) ? "0" + seconds : seconds);
            }

        if (distance <= 1 ){
            clearInterval(x);
            timeExpired();
        }
    }, 3);
    function timeExpired(){
        window.location.replace("quiz.php"); 
        unset($_SESSION['start_time']);// remove timer
    }