https://www.regione.campania.it/themes/custom/res/assets/js/gallery.js?tm530f

1(function($) {
2  let modalId = $('#image-gallery');
3
4  $(document)
5    .ready(function () {
6
7      loadGallery(true, 'a.thumbnail');
8
9      //This function disables buttons when needed
10      function disableButtons(counter_max, counter_current) {
11        $('#show-previous-image, #show-next-image')
12          .show();
13        if (counter_max === counter_current) {
14          $('#show-next-image')
15            .hide();
16        } else if (counter_current === 1) {
17          $('#show-previous-image')
18            .hide();
19        }
20      }
21
22      /**
23       *
24       * @param setIDs        Sets IDs when DOM is loaded. If using a PHP counter, set to false.
25       * @param setClickAttr  Sets the attribute for the click handler.
26       */
27
28      function loadGallery(setIDs, setClickAttr) {
29        let current_image,
30          selector,
31          counter = 0;
32
33        $('#show-next-image, #show-previous-image')
34          .click(function () {
35            if ($(this)
36              .attr('id') === 'show-previous-image') {
37              current_image--;
38            } else {
39              current_image++;
40            }
41
42            selector = $('[data-image-id="' + current_image + '"]');
43            updateGallery(selector);
44          });
45
46        function updateGallery(selector) {
47          let $sel = selector;
48          current_image = $sel.data('image-id');
49          $('#image-gallery-title')
50            .text($sel.data('title'));
51          $('#image-gallery-image')
52            .attr('src', $sel.data('image'));
53          disableButtons(counter, $sel.data('image-id'));
54        }
55
56        if (setIDs == true) {
57          $('[data-image-id]')
58            .each(function () {
59              counter++;
60              $(this)
61                .attr('data-image-id', counter);
62            });
63        }
64        $(setClickAttr)
65          .on('click', function () {
66            updateGallery($(this));
67          });
68      }
69    });
70
71  // build key actions
72  $(document)
73    .keydown(function (e) {
74      switch (e.which) {
75        case 37: // left
76          if ((modalId.data('bs.modal') || {})._isShown && $('#show-previous-image').is(":visible")) {
77            $('#show-previous-image')
78              .click();
79          }
80          break;
81
82        case 39: // right
83          if ((modalId.data('bs.modal') || {})._isShown && $('#show-next-image').is(":visible")) {
84            $('#show-next-image')
85              .click();
86          }
87          break;
88
89        default:
90          return; // exit this handler for other keys
91      }
92      e.preventDefault(); // prevent the default action (scroll / move caret)
93    });
94})(jQuery);