JS check for browser support

resources/scripts/header.js

@@ -1,6 +1,7 @@
 /*
 * Scroll up Header
 * Modified from https://codepen.io/sajjad/pen/vgEZNy
+* TODO: Convert to Vanilla JS
 */
 
 // Hide header on scroll down

resources/scripts/toc.js

@@ -6,6 +6,7 @@
  */
 
 const SmoothScroll = () => {
+    if (!'scrollBehavior' in document.documentElement.style) {
         const navLinks = document.querySelectorAll('#toc a');
 
         for (let n in navLinks) {
@@ -20,6 +21,7 @@ const SmoothScroll = () => {
             }
         }
     }
+}
 
 const ScrollSpy = () => {
     const sections = document.querySelectorAll('.mw-headline');
@@ -36,7 +38,26 @@ const ScrollSpy = () => {
     }
 }
 
-$(document).ready(function() {
+const CheckToC = () => {
+    var ToC = document.getElementById("toc");
+    if (toc) {
         SmoothScroll();
         ScrollSpy();
+    }
+}
+
+function ready(callbackFunc) {
+    if (document.readyState !== 'loading') {
+        CheckToC();
+    } else if (document.addEventListener) {
+        // All modern browsers to register DOMContentLoaded
+        document.addEventListener('DOMContentLoaded', callbackFunc);
+    } else {
+        // Old IE browsers
+        document.attachEvent('onreadystatechange', function() {
+            if (document.readyState === 'complete') {
+                CheckToC();
+            }
         });
+    }
+}