hugo-snap-gallery/static/js/snap-gallery.js

// Open the Modal
function openModal() {
  document.getElementsByClassName("snap-lightbox")[0].style.display = "block";
}

// Close the Modal
function closeModal() {
  document.getElementsByClassName("snap-lightbox")[0].style.display = "none";
}

var slideIndex = 1;
showSlides(slideIndex);

// Next/previous controls
function plusSlides(n) {
  showSlides(slideIndex += n);
}

// Thumbnail image controls
function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  var i;
  var slides = document.getElementsByClassName("snap-lightbox-inner");
  if (n > slides.length) { slideIndex = 1 }
  if (n < 1) { slideIndex = slides.length }
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  slides[slideIndex - 1].style.display = "inline-block";
}