chore: migrate many of our interactive scripts to defer

public/scripts/backbtn.js

@@ -0,0 +1,26 @@
+/* AFTER CHANGING THIS FILE, PLEASE MANUALLY MINIFY IT AND PUT INTO backbtn.min.js */
+/* TODO: Add minifier to build script */
+window.onload = () => {
+    const backBtn = document.querySelector('#backbtn');
+
+    let hasHistory = false;
+    window.addEventListener('beforeunload', () => {
+        hasHistory = true;
+    })
+
+    backBtn.addEventListener('click', () => {
+        if (!document.referrer) {
+            // This is the first page the user has visited on the site in this session
+            window.location.href = '/';
+            return;
+        }
+        history.back();
+
+        // User cannot go back, meaning that we're at the first page of the site session             
+        setTimeout(() => {
+            if (!hasHistory){
+                window.location.href = "/";
+            }
+        }, 200);
+    })
+}