66 lines
2.6 KiB
JavaScript
66 lines
2.6 KiB
JavaScript
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'use strict';
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// Simple offline service worker.
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//
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// On the main page include:
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// if ('serviceWorker' in navigator)
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// navigator.serviceWorker.register('simple-offline-service-worker.js');
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//
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// This cache always requests from the network to keep the cache fresh. There is a tradeoff here
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// because it'll wait ages for a slow network despite having a cached response ready to go. If stale
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// content is acceptable, use an 'eventually fresh' approach as described by Jake Archibald or
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// Nicolás Bevacqua in https://ponyfoo.com/articles/progressive-networking-serviceworker
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var version = 'v4.2.0';
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// To cache https://yoururl/subdirectory/ without listing index.html, use './'. If using a manifest,
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// 'start_url' should also be './'. You can also add additional files to this list.
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var offlineFiles = [ './' ];
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self.addEventListener('install', function(event) {
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// Cache our list of files.
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event.waitUntil(
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caches.open(version).then(function(cache) {
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return cache.addAll(offlineFiles).then(function() {
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return self.skipWaiting();
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});
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})
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);
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});
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// Remove any stale cache entries.
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self.addEventListener('activate', function(event) {
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event.waitUntil(
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caches.keys().then(function(keys) {
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return Promise.all(keys.map(function(key) {
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if (key !== version)
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return caches.delete(key);
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}));
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})
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);
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});
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self.addEventListener('fetch', function(event) {
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event.respondWith(
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// FIXME: We should send off the fetch request and check the cache in parallel.
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fetch(event.request).then(function(networkReponse) {
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// Check if this request is already in our cache. We only want to cache previously
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// cached items to prevent the cache from getting polluted.
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return caches.open(version).then(function(cache) {
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return cache.match(event.request).then(function(cachedResponse) {
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if (!cachedResponse)
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return networkReponse;
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// Clone the response since we're also returning it below.
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cache.put(event.request, networkReponse.clone());
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return networkReponse;
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});
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});
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}).catch(function(networkError) {
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return caches.open(version).then(function(cache) {
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return cache.match(event.request).then(function(cachedResponse) {
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return cachedResponse || networkError;
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});
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});
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})
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);
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});
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