sw.js

const CACHE_NAME = 'reddit-slideshow-v2';
const ASSETS = [
    './',
    './index.html',
    './style.css',
    './app.js',
    './manifest.json'
];

self.addEventListener('install', event => {
    self.skipWaiting(); // Forces the browser to activate this new version immediately
    event.waitUntil(
        caches.open(CACHE_NAME).then(cache => cache.addAll(ASSETS))
    );
});

self.addEventListener('activate', event => {
    // This deletes the old v1 cache so your updated app.js is finally recognized
    event.waitUntil(
        caches.keys().then(keys => Promise.all(
            keys.map(key => {
                if (key !== CACHE_NAME) return caches.delete(key);
            })
        ))
    );
});

self.addEventListener('fetch', event => {
    event.respondWith(
        caches.match(event.request).then(response => response || fetch(event.request))
    );
});