83 lines
No EOL
2.7 KiB
JavaScript
83 lines
No EOL
2.7 KiB
JavaScript
const addResourcesToCache = async (resources) => {
|
|
const cache = await caches.open('v1');
|
|
await cache.addAll(resources);
|
|
};
|
|
|
|
const putInCache = async (request, response) => {
|
|
const cache = await caches.open('v1');
|
|
await cache.put(request, response);
|
|
};
|
|
|
|
const cacheFirst = async ({ request, preloadResponsePromise, fallbackUrl }) => {
|
|
// First try to get the resource from the cache
|
|
const responseFromCache = await caches.match(request);
|
|
if (responseFromCache) {
|
|
return responseFromCache;
|
|
}
|
|
|
|
// Next try to use the preloaded response, if it's there
|
|
// NOTE: Chrome throws errors regarding preloadResponse, see:
|
|
// https://bugs.chromium.org/p/chromium/issues/detail?id=1420515
|
|
// https://github.com/mdn/dom-examples/issues/145
|
|
// To avoid those errors, remove or comment out this block of preloadResponse
|
|
// code along with enableNavigationPreload() and the "activate" listener.
|
|
const preloadResponse = await preloadResponsePromise;
|
|
if (preloadResponse) {
|
|
console.info('using preload response', preloadResponse);
|
|
putInCache(request, preloadResponse.clone());
|
|
return preloadResponse;
|
|
}
|
|
|
|
// Next try to get the resource from the network
|
|
try {
|
|
const responseFromNetwork = await fetch(request.clone());
|
|
// response may be used only once
|
|
// we need to save clone to put one copy in cache
|
|
// and serve second one
|
|
putInCache(request, responseFromNetwork.clone());
|
|
return responseFromNetwork;
|
|
} catch (error) {
|
|
const fallbackResponse = await caches.match(fallbackUrl);
|
|
if (fallbackResponse) {
|
|
return fallbackResponse;
|
|
}
|
|
// when even the fallback response is not available,
|
|
// there is nothing we can do, but we must always
|
|
// return a Response object
|
|
return new Response('Network error happened', {
|
|
status: 408,
|
|
headers: { 'Content-Type': 'text/plain' },
|
|
});
|
|
}
|
|
};
|
|
|
|
const enableNavigationPreload = async () => {
|
|
if (self.registration.navigationPreload) {
|
|
// Enable navigation preloads!
|
|
await self.registration.navigationPreload.enable();
|
|
}
|
|
};
|
|
|
|
self.addEventListener('activate', (event) => {
|
|
event.waitUntil(enableNavigationPreload());
|
|
});
|
|
|
|
self.addEventListener('install', (event) => {
|
|
event.waitUntil(
|
|
addResourcesToCache([
|
|
'./',
|
|
'./index.html',
|
|
'./favicon.ico'
|
|
])
|
|
);
|
|
});
|
|
|
|
self.addEventListener('fetch', (event) => {
|
|
event.respondWith(
|
|
cacheFirst({
|
|
request: event.request,
|
|
preloadResponsePromise: event.preloadResponse,
|
|
fallbackUrl: './index.html',
|
|
})
|
|
);
|
|
}); |