sw.js

var CACHE_NAME = 'v2';

var urlsToCache = [];

self.addEventListener('install', function (event) {
	// Perform install steps
	event.waitUntil(
		caches
			.open(CACHE_NAME)
			.then(function (cache) {
				console.log('Opened cache');
				return cache.addAll(urlsToCache);
			})
			.then(() => {
				console.log('Cache downloaded');
				self.skipWaiting();
			})
	);
});

self.addEventListener('fetch', function (event) {
	event.respondWith(
		caches.match(event.request).then(function (response) {
			// Cache hit - return response
			if (response) {
				return response;
			}
			console.log('cache miss', event.request.url);
			return fetch(event.request);
		})
	);
});

self.addEventListener('activate', function (event) {
	console.log('activated, remove unused cache...');
	var cacheAllowlist = [CACHE_NAME];
	event.waitUntil(
		caches.keys().then(function (cacheNames) {
			return Promise.all(
				cacheNames.map(function (cacheName) {
					if (cacheAllowlist.indexOf(cacheName) === -1) {
						console.log(cacheName);
						return caches.delete(cacheName);
					}
				})
			);
		})
	);
	clients.matchAll({ includeUncontrolled: true, type: 'window' }).then((arr) => {
		for (client of arr) {
			client.postMessage({ type: 'updated' });
		}
	});
});