Fix serviceworker to not so aggressively serve cached content

Author: chrisglein

sw.js

@@ -1,8 +1,6 @@
-// This is the service worker with the combined offline experience (Offline page + Offline copy of pages)
+// Service worker for offline fallback only (network-first)
 
-const CACHE = "pwabuilder-offline-page";
-
-importScripts('https://storage.googleapis.com/workbox-cdn/releases/5.1.2/workbox-sw.js');
+const CACHE = "pwabuilder-offline-page-v2";
 
 const offlineFallbackPage = "offline.html";
 
@@ -19,31 +17,25 @@ self.addEventListener('install', async (event) => {
   );
 });
 
-if (workbox.navigationPreload.isSupported()) {
-  workbox.navigationPreload.enable();
-}
-
-workbox.routing.registerRoute(
-  new RegExp('/*'),
-  new workbox.strategies.StaleWhileRevalidate({
-    cacheName: CACHE
-  })
-);
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((cacheNames) =>
+      Promise.all(
+        cacheNames
+          .filter((name) => name !== CACHE)
+          .map((name) => caches.delete(name))
+      )
+    )
+  );
+});
 
 self.addEventListener('fetch', (event) => {
   if (event.request.mode === 'navigate') {
     event.respondWith((async () => {
       try {
-        const preloadResp = await event.preloadResponse;
-
-        if (preloadResp) {
-          return preloadResp;
-        }
-
         const networkResp = await fetch(event.request);
         return networkResp;
       } catch (error) {
-
         const cache = await caches.open(CACHE);
         const cachedResp = await cache.match(offlineFallbackPage);
         return cachedResp;