js timer

timer.js

<h1>Countdown Clock</h1>
<div id="clockdiv">
  <div>
    <span class="days"></span>
    <div class="smalltext">Days</div>
  </div>
  <div>
    <span class="hours"></span>
    <div class="smalltext">Hours</div>
  </div>
  <div>
    <span class="minutes"></span>
    <div class="smalltext">Minutes</div>
  </div>
  <div>
    <span class="seconds"></span>
    <div class="smalltext">Seconds</div>
  </div>
</div>
CSS
body{
  text-align: center;
  background: #00ECB9;
  font-family: sans-serif;
  font-weight: 100;
}
 
h1{
  color: #396;
  font-weight: 100;
  font-size: 40px;
  margin: 40px 0px 20px;
}
 
#clockdiv{
  font-family: sans-serif;
  color: #fff;
  display: inline-block;
  font-weight: 100;
  text-align: center;
  font-size: 30px;
}
 
#clockdiv > div{
  padding: 10px;
  border-radius: 3px;
  background: #00BF96;
  display: inline-block;
}
 
#clockdiv div > span{
  padding: 15px;
  border-radius: 3px;
  background: #00816A;
  display: inline-block;
}
 
.smalltext{
  padding-top: 5px;
  font-size: 16px;
}
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 clock = document.getElementById(id);
  var daysSpan = clock.querySelector('.days');
  var hoursSpan = clock.querySelector('.hours');
  var minutesSpan = clock.querySelector('.minutes');
  var secondsSpan = clock.querySelector('.seconds');
 
  function updateClock() {
    var t = getTimeRemaining(endtime);
 
    daysSpan.innerHTML = t.days;
    hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
    minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
    secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);
 
    if (t.total <= 0) {
      clearInterval(timeinterval);
    }
  }
 
  updateClock();
  var timeinterval = setInterval(updateClock, 1000);
}
 
var deadline = new Date(Date.parse(new Date()) + 15 * 24 * 60 * 60 * 1000); // for endless timer
initializeClock('clockdiv', deadline);