Add image popup effect

_javascript/commons/img-link.js

@@ -1,8 +0,0 @@
-/*
- * Find the image links and mark them
- */
-
-$(function() {
-  const MARK = "img-link";
-  $("#main a").has("img").addClass(MARK);
-});

_javascript/utils/img-extra.js

@@ -0,0 +1,48 @@
+/**
+  Lazy load images (https://github.com/ApoorvSaxena/lozad.js)
+  and popup when clicked (https://github.com/dimsemenov/Magnific-Popup)
+*/
+
+$(function() {
+
+  const IMG_SCOPE = '#main > div.row:first-child > div:first-child';
+
+  if ($(`${IMG_SCOPE} img`).length <= 0 ) {
+    return;
+  }
+
+  /* lozy loading */
+
+  const imgs = document.querySelectorAll(`${IMG_SCOPE} img[data-src]`);
+  const observer = lozad(imgs);
+  observer.observe();
+
+  /* popup */
+
+  $(`${IMG_SCOPE} p > img[data-src],${IMG_SCOPE} img[data-src].preview-img`).each(
+    function() {
+      let nextTag = $(this).next();
+      const title = nextTag.prop('tagName') === 'EM' ? nextTag.text() : '';
+      const src = $(this).attr('data-src'); // created by lozad.js
+
+      $(this).wrap(`<a href="${src}" title="${title}" class="popup"></a>`);
+    }
+  );
+
+  $('.popup').magnificPopup({
+    type: 'image',
+    closeOnContentClick: true,
+    showCloseBtn: false,
+    zoom: {
+      enabled: true,
+      duration: 300,
+      easing: 'ease-in-out'
+    }
+  });
+
+
+  /* markup the image links */
+  $(`${IMG_SCOPE} a`).has("img").addClass('img-link');
+
+});
+