48 lines
1.6 KiB
JavaScript
48 lines
1.6 KiB
JavaScript
self.addEventListener("install", function(e) {
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return e.waitUntil(self.skipWaiting());
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});
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self.addEventListener("activate", function(e) {
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return e.waitUntil(self.clients.claim());
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});
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const addCoepHeaders = response => {
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const headers = new Headers(response.headers);
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headers.set("Cross-Origin-Embedder-Policy", "credentialless");
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headers.set("Cross-Origin-Opener-Policy", "same-origin");
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return new Response(response.body, {
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status: response.status,
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statusText: response.statusText,
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headers
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});
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};
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self.addEventListener("fetch", function(event) {
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if (event.request.mode === "navigate") {
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event.respondWith(
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(async () => {
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try {
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// First, try to use the navigation preload response if it's supported.
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const preloadResponse = await event.preloadResponse;
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if (preloadResponse) {
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return preloadResponse;
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}
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// Always try the network first.
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return addCoepHeaders(await fetch(event.request));
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} catch (error) {
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// catch is only triggered if an exception is thrown, which is likely
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// due to a network error.
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// If fetch() returns a valid HTTP response with a response code in
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// the 4xx or 5xx range, the catch() will NOT be called.
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console.log("Fetch failed; returning offline page instead.", error);
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const offline = { status: 200, statusText: "Worker is offline" };
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return new Response("Offline mode is not supported.", offline);
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}
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})()
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);
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} else {
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event.respondWith(fetch(event.request));
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}
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});
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