84 lines
2.4 KiB
JavaScript
84 lines
2.4 KiB
JavaScript
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const addResourcesToCache = async (resources) => {
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const cache = await caches.open("v1");
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await cache.addAll(resources);
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};
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const putInCache = async (request, response) => {
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const cache = await caches.open("v1");
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await cache.put(request, response);
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};
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const cacheFirst = async ({ request, preloadResponsePromise, fallbackUrl }) => {
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// First try to get the resource from the cache
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const responseFromCache = await caches.match(request);
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if (responseFromCache) {
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return responseFromCache;
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}
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// Next try to use the preloaded response, if it's there
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const preloadResponse = await preloadResponsePromise;
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if (preloadResponse) {
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console.info("using preload response", preloadResponse);
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putInCache(request, preloadResponse.clone());
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return preloadResponse;
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}
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// Next try to get the resource from the network
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try {
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const responseFromNetwork = await fetch(request.clone());
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// response may be used only once
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// we need to save clone to put one copy in cache
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// and serve second one
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putInCache(request, responseFromNetwork.clone());
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return responseFromNetwork;
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} catch (_error) {
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const fallbackResponse = await caches.match(fallbackUrl);
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if (fallbackResponse) {
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return fallbackResponse;
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}
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// when even the fallback response is not available,
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// there is nothing we can do, but we must always
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// return a Response object
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return new Response("Network error happened", {
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status: 408,
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headers: { "Content-Type": "text/plain" },
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});
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}
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};
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const enableNavigationPreload = async () => {
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if (self.registration.navigationPreload) {
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// Enable navigation preloads!
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await self.registration.navigationPreload.enable();
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}
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};
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self.addEventListener("activate", (event) => {
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event.waitUntil(enableNavigationPreload());
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});
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self.addEventListener("install", (event) => {
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event.waitUntil(
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addResourcesToCache([
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"./",
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"/index.html",
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"./global.css",
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"./prism-material-dark.css",
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"./placeholder.svg",
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"./grainy-gradient.png",
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"./fonts/work-sans-v18-latin-700.woff2",
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"./fonts/work-sans-v18-latin-regular.woff2",
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]),
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);
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});
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self.addEventListener("fetch", (event) => {
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event.respondWith(
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cacheFirst({
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request: event.request,
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preloadResponsePromise: event.preloadResponse,
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fallbackUrl: "/placeholder.svg",
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}),
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);
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});
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