var imageIndex = 0;
const IMAGE_COUNT = 5;
const CHANGE_IMAGE_SECONDS = 3;
function changeImage() {
  var src = $("img[alt='Stage']").attr("src");
  var baseUrl = src.substring(0, src.lastIndexOf("/") + 1);
  var imageName = src.substring(src.lastIndexOf("/") + 1, src.lastIndexOf(".") - 1);
  var extension = src.substring(src.lastIndexOf("."));
        
  imageIndex++;
  $("img[alt='Stage']").attr("src", baseUrl + imageName + (imageIndex % IMAGE_COUNT) + extension);
}

$(document).ready(function () {
  if ($("img[alt='Stage']").length > 0) {
    setInterval('changeImage()', CHANGE_IMAGE_SECONDS*1000);
  }
});