Test adding a service worked for PWA installing

index.html

@@ -154,5 +154,11 @@
         document.getElementById("fullscreen toggle").style.display = 'none';
       } 
     </script>
+
+    <script>
+      if('serviceWorker' in navigator) {
+        navigator.serviceWorker.register('/sw.js', { scope: '/' });
+      }
+    </script>
   </body>
 </html>

sw.js

@@ -0,0 +1,34 @@
+const CACHE_NAME = `v1`;
+
+// Use the install event to pre-cache all initial resources.
+self.addEventListener('install', event => {
+  event.waitUntil((async () => {
+    const cache = await caches.open(CACHE_NAME);
+    cache.addAll([
+      '/',
+    ]);
+  })());
+});
+
+self.addEventListener('fetch', event => {
+  event.respondWith((async () => {
+    const cache = await caches.open(CACHE_NAME);
+
+    // Get the resource from the cache.
+    const cachedResponse = await cache.match(event.request);
+    if (cachedResponse) {
+      return cachedResponse;
+    } else {
+        try {
+          // If the resource was not in the cache, try the network.
+          const fetchResponse = await fetch(event.request);
+
+          // Save the resource in the cache and return it.
+          cache.put(event.request, fetchResponse.clone());
+          return fetchResponse;
+        } catch (e) {
+          // The network failed.
+        }
+    }
+  })());
+});