var imgRotateInterval = 3000, id_imgrot;

function initPg() {
  id_imgrot = document.getElementById('img-rotator');
  if (id_imgrot) {
    setTimeout(imgRotate, imgRotateInterval);
  }
}

function imgRotate() {
  if (!!!id_imgrot) return;
  var imgArr = id_imgrot.getElementsByTagName('IMG'),
      i = 0;
  if (imgArr && imgArr.length > 0) {
    while (i < imgArr.length && imgArr[i].style.display !== 'block') i+=1;
    if (i < imgArr.length) {
      imgArr[i].style.display = 'none';
      i+= (i < imgArr.length-1) ? 1 : (-i);
      imgArr[i].style.display = 'block';
      setTimeout(imgRotate, imgRotateInterval);
    }
  }
}