sw.js

/* Sticky Notes service worker — app shell caching for offline use.
   Bump CACHE_VERSION whenever css/js/html changes ship. */
const CACHE_VERSION = 'sticky-notes-v3';
const APP_SHELL = [
    './',
    './index.html',
    './css/styles.css',
    './javascript/script.js',
    './manifest.webmanifest',
    './assets/icon.svg'
];

self.addEventListener('install', (event) => {
    event.waitUntil(
        caches.open(CACHE_VERSION)
            .then((cache) => cache.addAll(APP_SHELL))
            .then(() => self.skipWaiting())
    );
});

self.addEventListener('activate', (event) => {
    event.waitUntil(
        caches.keys()
            .then((keys) => Promise.all(
                keys.filter((key) => key !== CACHE_VERSION).map((key) => caches.delete(key))
            ))
            .then(() => self.clients.claim())
    );
});

// Stale-while-revalidate: serve from cache instantly, refresh the cache in the
// background so the next visit picks up deployed changes.
self.addEventListener('fetch', (event) => {
    const { request } = event;
    if (request.method !== 'GET') return;
    if (!request.url.startsWith('http')) return;

    event.respondWith(
        caches.open(CACHE_VERSION).then(async (cache) => {
            const cached = await cache.match(request, { ignoreSearch: true });
            const network = fetch(request)
                .then((response) => {
                    if (response && response.ok && (response.type === 'basic' || response.type === 'cors')) {
                        cache.put(request, response.clone());
                    }
                    return response;
                })
                .catch(() => cached);
            return cached || network;
        })
    );
});