// Slide navigation. Requires slides called slideXX.html .

function nextSlide() {
  var url = new String(window.location);
  var number = url.substr(url.length - 7, 2);
  number++;

  // We use a <span id='last_slide' /> to denote the last slide.
  if (document.getElementById &&
      document.getElementById('last_slide')) { return 0; }

  if (number.toString().length == 1) {
    number = "0" + number.toString();
  }
  window.location="slide" + number + ".html";
}

function prevSlide() {
  var url = new String(window.location);
  var number = url.substr(url.length - 7, 2);

  // Let's not run off the end of the slides
  if (number == 0) { return 0; }
  number--;

  if (number.toString().length == 1) {
    number = "0" + number.toString();
  }

  window.location="slide" + number + ".html";
}