const timestamp = '__timestamp__' const ASSETS = `assets_${timestamp}` const WEBPACK_ASSETS = `webpack_assets_${timestamp}` // `assets` is an array of everything in the `assets` directory const assets = __assets__ .map(file => file.startsWith('/') ? file : `/${file}`) .filter(filename => !filename.startsWith('/apple-icon')) .concat(['/index.html']) // `shell` is an array of all the files generated by webpack // also contains '/index.html' for some reason const webpackAssets = __shell__ .filter(filename => !filename.endsWith('.map')) .filter(filename => filename !== '/index.html') // `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 () => { await Promise.all([ caches.open(WEBPACK_ASSETS).then(cache => cache.addAll(webpackAssets)), caches.open(ASSETS).then(cache => cache.addAll(assets)) ]) self.skipWaiting() })()) }) self.addEventListener('activate', event => { event.waitUntil((async () => { let keys = await caches.keys() // delete old asset/ondemand caches for (let key of keys) { if (key !== ASSETS && !key.startsWith('webpack_assets_')) { await caches.delete(key) } } // for webpack assets, keep the two latest builds because we may need // them when the service worker has installed but the page has not // yet reloaded (e.g. when it gives the toast saying "please reload" // but then you don't refresh and instead load an async chunk) let webpackKeysToDelete = keys .filter(key => key.startsWith('webpack_assets_')) .sort((a, b) => { let aTimestamp = parseInt(a.substring(15), 10) let bTimestamp = parseInt(b.substring(15), 10) return bTimestamp < aTimestamp ? -1 : 1 }) .slice(2) for (let key of webpackKeysToDelete) { await caches.delete(key) } await self.clients.claim() })()) }) 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 () => { let sameOrigin = url.origin === self.origin if (sameOrigin) { // always serve webpack-generated resources and // assets from the cache if possible let response = await caches.match(req) if (response) { return response } // for routes, serve the /index.html file from the most recent // assets cache if (routes.find(route => route.pattern.test(url.pathname))) { let response = await caches.match('/index.html') if (response) { return response } } } // for everything else, go network-only return fetch(req) })()) })