// 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
}