perf: add throttle for scroll and resize listener

via https://www.30secondsofcode.org/js/s/throttle/

assets/js/back-to-top.js

@@ -1,7 +1,10 @@
 const backToTop = document.getElementById('back-to-top');
 
 if (backToTop !== null) {
-    window.addEventListener('scroll', function() {
-        window.scrollY > 100 ? backToTop.classList.add('show') : backToTop.classList.remove('show');
-    });
+    window.addEventListener(
+        'scroll',
+        throttle(function() {
+            window.scrollY > 100 ? backToTop.classList.add('show') : backToTop.classList.remove('show');
+        }, delayTime)
+    );
 }

assets/js/main.js

@@ -0,0 +1,24 @@
+// https://www.30secondsofcode.org/js/s/throttle/
+
+const throttle = (fn, wait) => {
+    let inThrottle, lastFn, lastTime;
+    return function() {
+        const context = this,
+              args = arguments;
+        if (!inThrottle) {
+            fn.apply(context, args);
+            lastTime = Date.now();
+            inThrottle = true;
+        } else {
+            clearTimeout(lastFn);
+            lastFn = setTimeout(function() {
+                if (Date.now() - lastTime >= wait) {
+                    fn.apply(context, args);
+                    lastTime = Date.now();
+                }
+            }, Math.max(wait - (Date.now() - lastTime), 0));
+        }
+    };
+};
+
+const delayTime = 420;

assets/js/nav-toggle.js

@@ -52,9 +52,19 @@ navCurtain.addEventListener('animationend', (e) => {
 
 // Close nav when window is scrolled or resized by user
 
-window.addEventListener('scroll', closeNav);
-
-window.addEventListener('resize', closeNav);
+window.addEventListener(
+    'scroll',
+    throttle(function() {
+        closeNav();
+    }, delayTime)
+);
+
+window.addEventListener(
+    'resize',
+    throttle(function() {
+        closeNav();
+    }, delayTime)
+);
 
 function closeNav() {
     if (navToggle.checked) {

assets/scss/components/_back-to-top.scss

@@ -14,7 +14,7 @@
 
 @if ($enableBackToTopAutoHide) {
     .back-to-top {
-        bottom: -5em;
+        bottom: -3.6em;
         transition: bottom 0.3s ease-in-out;
         &.show {
             bottom: 0;

exampleSite/resources/_gen/assets/scss/scss/main.scss_b04c21e44835e7dcdc8cb03d103b5ef1.json

@@ -1 +1 @@
-{"Target":"css/meme.min.fee27c7492b717ad2200531e61fca428c2153b6479073d07250c50c33b5c2604.css","MediaType":"text/css","Data":{"Integrity":"sha256-/uJ8dJK3F60iAFMeYfykKMIVO2R5Bz0HJQxQwztcJgQ="}}
+{"Target":"css/meme.min.becf25eee993457d079cf9cb1933804875c3ac89960278e671d97ba4930e4ce6.css","MediaType":"text/css","Data":{"Integrity":"sha256-vs8l7umTRX0HnPnLGTOASHXDrImWAnjmcdl7pJMOTOY="}}