const timestamp = '__timestamp__' const ASSETS = `cache${timestamp}` // `shell` is an array of all the files generated by webpack, // `assets` is an array of everything in the `assets` directory const toCache = __shell__.concat(__assets__) const cached = new Set(toCache) // `routes` is an array of `{ pattern: RegExp }` objects that // match the pages in your app const routes = __routes__ self.addEventListener('install', event => { event.waitUntil((async function () { let cache = await caches.open(ASSETS) await cache.addAll(toCache) self.skipWaiting() })()) }) self.addEventListener('activate', event => { event.waitUntil((async function () { let keys = await caches.keys() // delete old caches for (let key of keys) { if (key !== ASSETS) { await caches.delete(key) } } await self.clients.claim() })()) }) const CACHE_FIRST = [ '/system/accounts/avatars' ] self.addEventListener('fetch', event => { const req = event.request const url = new URL(req.url) // don't try to handle e.g. data: URIs if (!url.protocol.startsWith('http')) { return } event.respondWith((async function () { // always serve assets and webpack-generated files from cache if (cached.has(url.pathname)) { return caches.match(req) } // for pages, you might want to serve a shell `index.html` file, // which Sapper has generated for you. It's not right for every // app, but if it's right for yours then uncomment this section if (url.origin === self.origin && routes.find(route => route.pattern.test(url.pathname))) { return caches.match('/index.html') } // For these GET requests, go cache-first if (req.method === 'GET' && CACHE_FIRST.some(pattern => url.pathname.startsWith(pattern))) { let cache = await caches.open(`offline${timestamp}`) let response = await cache.match(req) if (response) { // update asynchronously fetch(req).then(response => { cache.put(req, response.clone()) }) return response } response = await fetch(req) cache.put(req, response.clone()) return response } // for everything else, go network-only return fetch(req) })()) })