improve mobile footer

assets/js/script.js

@@ -9,16 +9,36 @@ function getUnit(id) {
   return pxUnit;
 }
 
-function throttle(callback, limit) {
-  let waiting = false;
+// Throttle found here : https://gist.github.com/ionurboz/51b505ee3281cd713747b4a84d69f434
+function throttle(func, wait, options) {
+  var context, args, result;
+  var timeout = null;
+  var previous = 0;
+  if (!options) options = {};
+  var later = function () {
+    previous = options.leading === false ? 0 : Date.now();
+    timeout = null;
+    result = func.apply(context, args);
+    if (!timeout) context = args = null;
+  };
   return function () {
-    if (!waiting) {
-      callback.apply(this, arguments);
-      waiting = true;
-      setTimeout(function () {
-        waiting = false;
-      }, limit);
+    var now = Date.now();
+    if (!previous && options.leading === false) previous = now;
+    var remaining = wait - (now - previous);
+    context = this;
+    args = arguments;
+    if (remaining <= 0 || remaining > wait) {
+      if (timeout) {
+        clearTimeout(timeout);
+        timeout = null;
+      }
+      previous = now;
+      result = func.apply(context, args);
+      if (!timeout) context = args = null;
+    } else if (!timeout && options.trailing !== false) {
+      timeout = setTimeout(later, remaining);
     }
+    return result;
   };
 }
 
@@ -47,6 +67,17 @@ function toggleLogoState() {
     document.querySelector("#main-header").classList.remove("minimized");
   }
 }
+function toggleFooterState() {
+  if (scrollY > 90) {
+    document
+      .querySelector("#main-footer")
+      .classList.add("main-footer--background");
+  } else {
+    document
+      .querySelector("#main-footer")
+      .classList.remove("main-footer--background");
+  }
+}
 
 function fixFootNotes() {
   const footnotes = document.querySelectorAll('a[href^="#sdfootnote"]');
@@ -108,9 +139,13 @@ document.addEventListener("DOMContentLoaded", () => {
     top: 0,
   });
 
-  window.addEventListener("scroll", () => {
+  const handleScroll = throttle(() => {
     toggleLogoState();
-  });
+    if (window.innerWidth <= 680) {
+      toggleFooterState();
+    }
+  }, 100);
+  window.addEventListener("scroll", handleScroll);
 
   setWindowHeightFactor();
   window.addEventListener("resize", () => {
@@ -168,6 +203,4 @@ document.addEventListener("DOMContentLoaded", () => {
   navOverlay.addEventListener("click", () => {
     closeNav();
   });
-
-  subscribeBtn.addEventListener("click", showSubscribeField);
 });