Script for inline day countdown counter

day-counter.html

<p id="counter1">Only <span class="days"></span> days left</p>

<script>
    function getTimeRemaining(endtime) {
        const now = new Date().getTime();
        const t = endtime - now;
        const days = Math.floor(t / (1000 * 60 * 60 * 24));
        return {
            'total': t,
            'days': days,
        };
    }

    function initializeClock(element, endtime) {
        const clock = document.querySelector(element);
        const daysSpan = clock.querySelector('.days');

        function updateClock() {
            const t = getTimeRemaining(endtime);
            daysSpan.innerHTML = t.days;
            if (t.total <= 0) {
                clearInterval(timeinterval);
            }
        }
        updateClock();
        const timeinterval = setInterval(updateClock, 1000);
    }
    
    /* Declare deadline time */
    const deadline = new Date("2019-01-31").getTime()
    /* Trigger counter function by targeting specific element and passing the above deadline */
    initializeClock('#counter1', deadline);
</script>