cache.js

const cacheName = "cache4"; // Change value to force update

self.addEventListener("install", (event) => {
  // Kick out the old service worker
  self.skipWaiting();

  event.waitUntil(
    caches.open(cacheName).then((cache) => {
      return cache.addAll([
        "./",
        "./index.html",
        "./locked.html",
        "./android-chrome-36x36.png", // Favicon, Android Chrome M39+ with 0.75 screen density
        "./android-chrome-144x144.png", // Favicon, Android Chrome M39+ with 0.75 screen density
        "./js/accelerometer.js",
        "./js/gps.js",
        "./js/passcode_handler.js",
        "./manifest.json",
      ]);
    })
  );
});

self.addEventListener("activate", (event) => {
  // Delete any non-current cache
  event.waitUntil(
    caches.keys().then((keys) => {
      Promise.all(
        keys.map((key) => {
          if (![cacheName].includes(key)) {
            return caches.delete(key);
          }
        })
      );
    })
  );
});

// Offline-first, cache-first strategy
// Kick off two asynchronous requests, one to the cache and one to the network
// If there's a cached version available, use it, but fetch an update for next time.
// Gets data on screen as quickly as possible, then updates once the network has returned the latest data.
self.addEventListener("fetch", (event) => {
  event.respondWith(
    caches.open(cacheName).then((cache) => {
      return cache.match(event.request).then((response) => {
        return (
          response ||
          fetch(event.request).then((networkResponse) => {
            cache.put(event.request, networkResponse.clone());
            return networkResponse;
          })
        );
      });
    })
  );
});