Replace Disqus lazy loading plugin with native JS

_includes/disqus.html

@@ -1,25 +1,33 @@
 <!--
   The Disqus lazy loading.
-  Powered by: <https://github.com/osvaldasvalutis/disqusLoader.js>
 -->
 
-<div id="disqus" class="pt-2 pb-2">
-  <p class="text-center text-muted small pb-5">
+<div id="disqus_thread" class="pt-2 pb-2">
+  <p class="text-center text-muted small mb-5">
     Comments powered by <a href="https://disqus.com/">Disqus</a>.
   </p>
 </div>
 
-<script src="{{ '/assets/js/lib/jquery.disqusloader.min.js' | relative_url }}"></script>
-<script>
-  const options = {
-    scriptUrl: '//{{ site.disqus.shortname }}.disqus.com/embed.js',
-
-    disqusConfig: function() {
-      this.page.title = '{{ page.title }}';
-      this.page.url = '{{ page.url | absolute_url }}';
-      this.page.identifier = '{{ page.url }}';
-    }
+<script type="text/javascript">
+  var disqus_config = function () {
+    this.page.url = '{{ page.url | absolute_url }}';
+    this.page.identifier = '{{ page.url }}';
   };
 
-  $.disqusLoader('#disqus', options);
+  /* Lazy loading */
+
+  var disqus_observer = new IntersectionObserver(function (entries) {
+    if(entries[0].isIntersecting) {
+        (function () {
+            var d = document, s = d.createElement('script');
+            s.src = 'https://{{ site.disqus.shortname }}.disqus.com/embed.js';
+            s.setAttribute('data-timestamp', +new Date());
+            (d.head || d.body).appendChild(s);
+        })();
+
+        disqus_observer.disconnect();
+    }
+  }, { threshold: [0] });
+
+  disqus_observer.observe(document.querySelector("#disqus_thread"));
 </script>