old_contents: var imageSelector = [
      'tr:not(.parent) td.indexcolname a[href$=".png"]',
      'tr:not(.parent) td.indexcolname a[href$=".jpg"]',
      'tr:not(.parent) td.indexcolname a[href$=".jpeg"]',
  ].join(', ');
  
  lightGallery(document.getElementById('indexlist'), {
      selector: imageSelector,
      mode: 'lg-slide',
      hideBarsDelay: 2000,
      loop: false,
      hideControlOnEnd: true,
      download: true,
      cssEasing : 'cubic-bezier(0.25, 0, 0.25, 1)'
  });
  
new_contents: var imageSelector = [
      'tr:not(.parent) td.indexcolname a[href$=".png"]',
      'tr:not(.parent) td.indexcolname a[href$=".jpg"]',
      'tr:not(.parent) td.indexcolname a[href$=".gif"]',
  ].join(', ');
  
  lightGallery(document.getElementById('indexlist'), {
      selector: imageSelector,
      mode: 'lg-slide',
      hideBarsDelay: 2000,
      loop: false,
      hideControlOnEnd: true,
      download: true,
      cssEasing : 'cubic-bezier(0.25, 0, 0.25, 1)'
  });
  
subject: add gif extension to image gallery viewer