sw.js

const cacheName = "nasPrviPWA-v1";

const OFFLINE_URL = "/PWAfrontend2022/offline.html";

self.addEventListener("install", (e) => {
  console.log("[Service Worker] Install");
  e.waitUntil(
    (async () => {
      const cache = await caches.open(cacheName);
      console.log("[Service Worker] Caching all: app shell and content");
      await cache.add(new Request(OFFLINE_URL, { cache: "reload" }));
    })()
  );
});

self.addEventListener("fetch", (e) => {
  e.respondWith(
    (async () => {
      try {
        const r = await caches.match(e.request);
        console.log(`[Service Worker] Fetching resource: ${e.request.url}`);
        if (r) {
          return r;
        }
        const response = await fetch(e.request);
        const cache = await caches.open(cacheName);
        console.log(`[Service Worker] Caching new resource: ${e.request.url}`);
        cache.put(e.request, response.clone());
        return response;
      } catch (error) {
        console.log("Fetch failed; returning offline page instead.", error);

        const cache = await caches.open(cacheName);
        const cachedResponse = await cache.match(OFFLINE_URL);
        return cachedResponse;
      }
    })()
  );
});