JSFiddle - React, Tailwind, and code Playground

by Alex

HTML

<div class="timer" data-date="31.05.2016">
		<div class="line">
			<div class="name">
				До конца акции осталось:</div>
			<div>
				<div class="days val">
					&nbsp;</div>
				<div class="smalltext">
					Дней</div>
			</div>
		</div>
		<div class="line bottom">
			<div>
				<div class="hours val">
					&nbsp;</div>
				<div class="smalltext">
					Часов</div>
			</div>
			<div>
				<div class="minutes val">
					&nbsp;</div>
				<div class="smalltext">
					Минут</div>
			</div>
			<div>
				<div class="seconds val">
					&nbsp;</div>
				<div class="smalltext">
					Секунд</div>
			</div>
		</div>
	</div>

JavaScript

function getTimeRemaining(endtime) {
  var t = Date.parse(endtime) - Date.parse(new Date());
  var seconds = Math.floor((t / 1000) % 60);
  var minutes = Math.floor((t / 1000 / 60) % 60);
  var hours = Math.floor((t / (1000 * 60 * 60)) % 24);
  var days = Math.floor(t / (1000 * 60 * 60 * 24));
  return {
    'total': t,
    'days': days,
    'hours': hours,
    'minutes': minutes,
    'seconds': seconds
  };
}

function initializeClock(id, endtime) {
  var endtimeFromEl = $('.'+id).data('date') || 0;
  
  if (endtimeFromEl != 0) {
    parts = endtimeFromEl.split('.');
    endtimeFromEl = new Date(parts[2], parts[1]-1, parts[0]);
  }
  
  endtime = endtime || endtimeFromEl;

  var clock = $('.'+id);
  var daysSpan = clock.find('.days');
  var hoursSpan = clock.find('.hours');
  var minutesSpan = clock.find('.minutes');
  var secondsSpan = clock.find('.seconds');

  function updateClock() {
    var t = getTimeRemaining(endtime);

    daysSpan.html(('0' + t.days).slice(-2));
    hoursSpan.html(('0' + t.hours).slice(-2));
    minutesSpan.html(('0' + t.minutes).slice(-2));
    secondsSpan.html(('0' + t.seconds).slice(-2));

    if (t.total <= 0) {
      clearInterval(timeinterval);
    }
  }

  updateClock();
  var timeinterval = setInterval(updateClock, 1000);
}

initializeClock('timer');