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f8305f53c7
The special offline page with fetch interception in service worker is only strongly required on Android ad a pre-req for PWAs This is now strongly restricted only to Android while iOS PWA support gets better Long term if we build offline support we can unlock it more globally
192 lines
6.7 KiB
Plaintext
192 lines
6.7 KiB
Plaintext
'use strict';
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// Special offline and fetch interception is restricted to Android only
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// we have had a large amount of pain supporting this on Firefox / Safari
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// it is only strongly required on Android, when PWA gets better on iOS
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// we can unlock it there as well, for Desktop we can consider unlocking it
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// if we start supporting offline browsing for laptops
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if (/(android)/i.test(navigator.userAgent)) {
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// Incrementing CACHE_VERSION will kick off the install event and force previously cached
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// resources to be cached again.
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const CACHE_VERSION = 1;
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const CURRENT_CACHES = {
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offline: 'offline-v' + CACHE_VERSION
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};
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const OFFLINE_URL = 'offline.html';
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const createCacheBustedRequest = function(url) {
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var headers = new Headers({
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'Discourse-Track-View': '0'
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});
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var request = new Request(url, {cache: 'reload', headers: headers});
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// See https://fetch.spec.whatwg.org/#concept-request-mode
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// This is not yet supported in Chrome as of M48, so we need to explicitly check to see
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// if the cache: 'reload' option had any effect.
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if ('cache' in request) {
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return request;
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}
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// If {cache: 'reload'} didn't have any effect, append a cache-busting URL parameter instead.
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var bustedUrl = new URL(url, self.location.href);
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bustedUrl.search += (bustedUrl.search ? '&' : '') + 'cachebust=' + Date.now();
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return new Request(bustedUrl, {headers: headers});
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}
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self.addEventListener('install', function(event) {
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event.waitUntil(
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// We can't use cache.add() here, since we want OFFLINE_URL to be the cache key, but
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// the actual URL we end up requesting might include a cache-busting parameter.
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fetch(createCacheBustedRequest(OFFLINE_URL)).then(function(response) {
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return caches.open(CURRENT_CACHES.offline).then(function(cache) {
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return cache.put(OFFLINE_URL, response);
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});
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}).then(function(cache) {
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self.skipWaiting();
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})
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);
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});
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self.addEventListener('activate', function(event) {
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// Delete all caches that aren't named in CURRENT_CACHES.
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// While there is only one cache in this example, the same logic will handle the case where
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// there are multiple versioned caches.
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var expectedCacheNames = Object.keys(CURRENT_CACHES).map(function(key) {
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return CURRENT_CACHES[key];
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});
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event.waitUntil(
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caches.keys().then(function(cacheNames) {
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return Promise.all(
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cacheNames.map(function(cacheName) {
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if (expectedCacheNames.indexOf(cacheName) === -1) {
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// If this cache name isn't present in the array of "expected" cache names,
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// then delete it.
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return caches.delete(cacheName);
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}
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})
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);
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}).then(function() {
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self.clients.claim()
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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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// Bypass service workers if this is a url with a token param
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if(/\?.*token/i.test(event.request.url)) {
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return;
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}
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// We only want to call event.respondWith() if this is a navigation request
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// for an HTML page.
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// request.mode of 'navigate' is unfortunately not supported in Chrome
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// versions older than 49, so we need to include a less precise fallback,
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// which checks for a GET request with an Accept: text/html header.
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if (event.request.mode === 'navigate' ||
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(event.request.method === 'GET' &&
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event.request.headers.get('accept').includes('text/html'))) {
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event.respondWith(
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fetch(event.request).catch(function(error) {
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// The catch is only triggered if fetch() throws an exception, which will most likely
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// happen due to the server being unreachable.
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// If fetch() returns a valid HTTP response with an response code in the 4xx or 5xx
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// range, the catch() will NOT be called. If you need custom handling for 4xx or 5xx
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// errors, see https://github.com/GoogleChrome/samples/tree/gh-pages/service-worker/fallback-response
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if (!navigator.onLine) {
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return caches.match(OFFLINE_URL);
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} else {
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throw new Error(error);
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}
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})
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);
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}
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// If our if() condition is false, then this fetch handler won't intercept the request.
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// If there are any other fetch handlers registered, they will get a chance to call
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// event.respondWith(). If no fetch handlers call event.respondWith(), the request will be
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// handled by the browser as if there were no service worker involvement.
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});
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}
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const idleThresholdTime = 1000 * 10; // 10 seconds
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var lastAction = -1;
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function isIdle() {
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return lastAction + idleThresholdTime < Date.now();
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}
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function showNotification(title, body, icon, badge, tag, baseUrl, url) {
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var notificationOptions = {
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body: body,
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icon: icon,
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badge: badge,
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data: { url: url, baseUrl: baseUrl },
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tag: tag
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}
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return self.registration.showNotification(title, notificationOptions);
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}
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self.addEventListener('push', function(event) {
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var payload = event.data.json();
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if(!isIdle() && payload.hide_when_active) {
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return false;
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}
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event.waitUntil(
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self.registration.getNotifications({ tag: payload.tag }).then(function(notifications) {
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if (notifications && notifications.length > 0) {
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notifications.forEach(function(notification) {
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notification.close();
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});
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}
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return showNotification(payload.title, payload.body, payload.icon, payload.badge, payload.tag, payload.base_url, payload.url);
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})
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);
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});
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self.addEventListener('notificationclick', function(event) {
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// Android doesn't close the notification when you click on it
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// See: http://crbug.com/463146
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event.notification.close();
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var url = event.notification.data.url;
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var baseUrl = event.notification.data.baseUrl;
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// This looks to see if the current window is already open and
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// focuses if it is
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event.waitUntil(
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clients.matchAll({ type: "window" })
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.then(function(clientList) {
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var reusedClientWindow = clientList.some(function(client) {
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if (client.url === baseUrl + url && 'focus' in client) {
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client.focus();
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return true;
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}
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if ('postMessage' in client && 'focus' in client) {
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client.focus();
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client.postMessage({ url: url });
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return true;
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}
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return false;
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});
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if (!reusedClientWindow && clients.openWindow) return clients.openWindow(baseUrl + url);
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})
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);
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});
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self.addEventListener('message', function(event) {
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if('lastAction' in event.data){
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lastAction = event.data.lastAction;
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}});
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<% DiscoursePluginRegistry.service_workers.each do |js| %>
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<%=raw "#{File.read(js)}" %>
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<% end %>
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