(function () {
  var track = document.getElementById('hdcSlides');
  if (!track) return;
  var slides = track.children, n = slides.length, i = 0;
  var dots = document.querySelectorAll('#hdcDots button');
  function go(x) {
    i = (x + n) % n;
    track.style.transform = 'translateX(-' + (i * 100) + '%)';
    dots.forEach(function (d, k) { d.classList.toggle('active', k === i); });
  }
  var prev = document.getElementById('hdcPrev'), next = document.getElementById('hdcNext');
  if (prev) prev.addEventListener('click', function () { go(i - 1); });
  if (next) next.addEventListener('click', function () { go(i + 1); });
  dots.forEach(function (d) { d.addEventListener('click', function () { go(+d.getAttribute('data-idx')); }); });
  if (n > 1) setInterval(function () { go(i + 1); }, 6000);
})();