Stock Countdown Text

custom.html

<p style="font-size:16px; text-align: right; color: #303030;">Just <span class="stockCountdown" style="font-weight:bold; color: black;">15</span> left in stock</p>
<script>
document.addEventListener("DOMContentLoaded", function () {
    var minute = 15;
    var sec = 6;
    setInterval(function() {
        document.querySelectorAll(".stockCountdown").forEach(el => {
            el.innerHTML = minute;
        });
        sec--;
        if (sec == 00) {
            minute --;
            sec = 60;
            if (minute == 0) {
                minute = 5;
            }
        }
    }, 1000);
});
</script>