81 lines
2.3 KiB
TypeScript
81 lines
2.3 KiB
TypeScript
/// <reference lib="webworker" />
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import { build, files, timestamp } from '$service-worker';
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const worker = (self as unknown) as ServiceWorkerGlobalScope;
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const FILES = `cache${timestamp}`;
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// `build` is an array of all the files generated by the bundler,
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// `files` is an array of everything in the `static` directory
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const to_cache = build.concat(files);
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const staticAssets = new Set(to_cache);
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worker.addEventListener('install', (event) => {
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event.waitUntil(
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caches
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.open(FILES)
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.then((cache) => cache.addAll(to_cache))
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.then(() => {
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worker.skipWaiting();
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})
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);
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});
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worker.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 !== FILES) await caches.delete(key);
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}
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worker.clients.claim();
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})
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);
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});
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/**
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* Fetch the asset from the network and store it in the cache.
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* Fall back to the cache if the user is offline.
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*/
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async function fetchAndCache(request: Request) {
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const cache = await caches.open(`offline${timestamp}`);
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try {
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const response = await fetch(request);
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cache.put(request, response.clone());
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return response;
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} catch (err) {
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const response = await cache.match(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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worker.addEventListener('fetch', (event) => {
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if (event.request.method !== 'GET' || event.request.headers.has('range')) return;
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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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const isHttp = url.protocol.startsWith('http');
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const isDevServerRequest =
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url.hostname === self.location.hostname && url.port !== self.location.port;
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const isStaticAsset = url.host === self.location.host && staticAssets.has(url.pathname);
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const skipBecauseUncached = event.request.cache === 'only-if-cached' && !isStaticAsset;
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if (isHttp && !isDevServerRequest && !skipBecauseUncached) {
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event.respondWith(
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(async () => {
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// always serve static files and bundler-generated assets from cache.
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// if your application has other URLs with data that will never change,
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// set this variable to true for them and they will only be fetched once.
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const cachedAsset = isStaticAsset && (await caches.match(event.request));
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return cachedAsset || fetchAndCache(event.request);
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})()
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);
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}
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});
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