simplify toc and remove post title from it

Highlight all sections on sight instead of last one to intersect

static/js/table-of-contents.js

@@ -1,29 +1,13 @@
-function elementInToC(entry) {
-  return document.querySelector(`#TableOfContents ul li a[href="#${entry.target.getAttribute('id')}"]`);
-}
-
 window.addEventListener('DOMContentLoaded', () => {
-  var previousActive = null;
-
   const observer = new IntersectionObserver(entries => {
-    var foundActive = false;
     entries.forEach(entry => {
-      if (!foundActive && entry.isIntersecting) {
-        if (previousActive) {
-          previousActive.classList.remove('active');
-        }
-        elementInToC(entry).classList.add('active');
-        foundActive = true;
-        previousActive = elementInToC(entry);
+      const id = entry.target.getAttribute('id');
+      if (entry.intersectionRatio > 0) {
+        document.querySelector(`#TableOfContents ul li a[href="#${id}"]`).classList.add('active');
+      } else {
+        document.querySelector(`#TableOfContents ul li a[href="#${id}"]`).classList.remove('active');
       }
-      else {
-        elementInToC(entry).classList.remove('active');
-      }
-    })
-
-    if (!foundActive) {
-      previousActive.classList.add('active');
-    };
+    });
   });
 
   // Track all headers that have an `id` applied
@@ -31,12 +15,3 @@ window.addEventListener('DOMContentLoaded', () => {
     observer.observe(section);
   });
 });
-
-// Post title doesn't get parsed as it is not part of the content file
-(function addPostTitle2ToC() {
-  var toc = document.getElementById('TableOfContents');
-  if (!toc) return;
-  var title = document.getElementById("post__title").innerText;
-  var ul = toc.querySelector('ul');
-  ul.outerHTML = `<ul><li><a href="#post__title" class="active">${title}</a>${ul.outerHTML}</li></ul>`;
-})();