service-worker.js

const CACHE_NAME = "my-app-cache-v1";
const urlsToCache = ["/", "/index.html", "/styles.css", "/script.js"];

// Install the service worker
self.addEventListener("install", event => {
  event.waitUntil(
    caches.open(CACHE_NAME).then(cache => {
      return cache.addAll(urlsToCache);
    })
  );
});

// Cache and return requests
self.addEventListener("fetch", event => {
  event.respondWith(
    caches.match(event.request).then(response => {
      return response || fetch(event.request);
    })
  );
});

// Update a service worker
self.addEventListener("activate", event => {
  const cacheWhitelist = [CACHE_NAME];
  event.waitUntil(
    caches.keys().then(cacheNames => {
      return Promise.all(
        cacheNames.map(cacheName => {
          if (!cacheWhitelist.includes(cacheName)) {
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
});