add sw

index.html

@@ -26,5 +26,21 @@ <h4>when to use</h4>
         <li>less user interactivity</li>
       </ul>
     </section>
+
+    <script>
+      if ("serviceWorker" in navigator) {
+        navigator.serviceWorker
+          .register("/sw.js")
+          .then((registration) =>
+            console.log(
+              "Service Worker registered with scope:",
+              registration.scope
+            )
+          )
+          .catch((error) =>
+            console.error("Service Worker registration failed:", error)
+          );
+      }
+    </script>
   </body>
 </html>

sw.js

@@ -0,0 +1,19 @@
+const CACHE_NAME = 'my-cache-v0';
+const urlsToCache = [
+  '/',
+  '/index.html'
+];
+
+self.addEventListener('install', event => {
+  event.waitUntil(
+    caches.open(CACHE_NAME)
+      .then(cache => cache.addAll(urlsToCache))
+  );
+});
+
+self.addEventListener('fetch', event => {
+  event.respondWith(
+    caches.match(event.request)
+      .then(response => response || fetch(event.request))
+  );
+});