How to add timer to bootstrap progress bar in javascript

Question

I have a timer with the progress bar. the timer works fine. but I want to move the progress bar with the timer. I'm using the bootstrap progress bar. if I remove the bar variable from the function the timer works fine but with the progress, it stops working. any suggestions? thank you :)

function startTimer(duration, display, bar) {
    var timer = duration, minutes, seconds;
    setInterval(function () {
        minutes = parseInt(timer / 60, 10);
        seconds = parseInt(timer % 60, 10);

        minutes = minutes < 10 ? "0" + minutes : minutes;
        seconds = seconds < 10 ? "0" + seconds : seconds;

        display.textContent = minutes + ":" + seconds;
        bar.css('width', minutes + '%');

        if (--timer < 0) {
            timer = duration;
        }
    }, 1000);
}

window.onload = function () {
    var minutes = 60 * 15,
    display = document.querySelector('#time');
    bar = document.querySelector('#progressBar');
    startTimer(minutes, display, bar);
};

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">

<div class="progress mx-auto mb-2" style="max-width: 300px;">
    <div class="progress-bar bg-success" role="progressbar" id="progressBar" style="width: 100%" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100"></div>
</div>
<span id="time">15:00</span>

Answer 1

Use bar.style.width, .css() is a jQuery function.

For correct percentage, calculate total and remaining seconds and set bar width based on that

function startTimer(duration, display, bar) {
    var timer = duration, minutes, seconds;
    setInterval(function () {
        minutes = parseInt(timer / 60, 10);
        seconds = parseInt(timer % 60, 10);
        
        var totalSeconds = 15 * 60
        , remainingSeconds = minutes * 60 + seconds
        
        bar.style.width = (remainingSeconds*100/totalSeconds) + "%";
        
        minutes = minutes < 10 ? "0" + minutes : minutes;
        seconds = seconds < 10 ? "0" + seconds : seconds;

        display.textContent = minutes + ":" + seconds;

        if (--timer < 0) {
            timer = duration;
        }
    }, 1000);
}

window.onload = function () {
    var minutes = 60 * 15,
    display = document.querySelector('#time');
    bar = document.querySelector('#progressBar');
    startTimer(minutes, display, bar);
};

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">

<div class="progress mx-auto mb-2" style="max-width: 300px;">
    <div class="progress-bar bg-success" role="progressbar" id="progressBar" style="width: 100%" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100"></div>
</div>
<span id="time">15:00</span>