78 lines
2 KiB
JavaScript
78 lines
2 KiB
JavaScript
const timestamp = '__timestamp__';
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const ASSETS = `cache${timestamp}`;
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// `shell` is an array of all the files generated by webpack,
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// `assets` is an array of everything in the `assets` directory
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const to_cache = __shell__.concat(__assets__);
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const cached = new Set(to_cache);
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// `routes` is an array of `{ pattern: RegExp }` objects that
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// match the pages in your app
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const routes = __routes__;
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self.addEventListener('install', event => {
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event.waitUntil(
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caches
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.open(ASSETS)
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.then(cache => cache.addAll(to_cache))
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.then(() => {
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self.skipWaiting();
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})
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);
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});
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self.addEventListener('activate', event => {
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event.waitUntil(
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caches.keys().then(async keys => {
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// delete old caches
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for (const key of keys) {
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if (key !== ASSETS) await caches.delete(key);
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}
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await self.clients.claim();
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})
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);
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});
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self.addEventListener('fetch', event => {
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const url = new URL(event.request.url);
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// don't try to handle e.g. data: URIs
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if (!url.protocol.startsWith('http')) return;
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// always serve assets and webpack-generated files from cache
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if (cached.has(url.pathname)) {
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event.respondWith(caches.match(event.request));
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return;
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}
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// for pages, you might want to serve a shell `index.html` file,
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// which Sapper has generated for you. It's not right for every
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// app, but if it's right for yours then uncomment this section
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/*
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if (url.origin === self.origin && routes.find(route => route.pattern.test(url.pathname))) {
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event.respondWith(caches.match('/index.html'));
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return;
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}
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*/
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// for everything else, try the network first, falling back to
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// cache if the user is offline. (If the pages never change, you
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// might prefer a cache-first approach to a network-first one.)
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event.respondWith(
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caches
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.open(`offline${timestamp}`)
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.then(async cache => {
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try {
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const response = await fetch(event.request);
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cache.put(event.request, response.clone());
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return response;
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} catch(err) {
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const response = await cache.match(event.request);
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if (response) return response;
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throw err;
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}
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})
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);
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});
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