Cache tiles locally within the ServiceWorker. Fix #40.
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76f54932bf
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11
src/App.vue
11
src/App.vue
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@ -172,8 +172,15 @@ export default {
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},
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},
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mounted() {
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if ('serviceWorker' in navigator) {
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runtime.register().catch((error) => {
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// Service worker is for caching only, so it needs both SW support and
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// caching API support.
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if ('serviceWorker' in navigator && 'caches' in window) {
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runtime.register().then(
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// Clean expired tiles from the cache at startup
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() => navigator.serviceWorker.controller.postMessage(JSON.stringify({
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action: 'PURGE_EXPIRED_TILES',
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})),
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).catch((error) => {
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console.log(`Registration failed with ${error}.`);
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});
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}
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182
src/sw.js
182
src/sw.js
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@ -1,4 +1,10 @@
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import { VERSION as CACHE_NAME } from '@/constants';
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import localforage from 'localforage';
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import {
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TILE_SERVERS,
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VERSION as CACHE_NAME,
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} from '@/constants';
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import { loadDataFromStorage } from '@/storage';
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const DEBUG = (process.env.NODE_ENV !== 'production');
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@ -17,11 +23,52 @@ assetsToCache = assetsToCache.filter(
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const ALLOW_CACHING_FROM = [
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global.location.origin,
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];
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const TILE_SERVERS_ORIGINS = [];
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// Allow alterations of tile servers requests
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Object.keys(TILE_SERVERS).forEach((tileServer) => {
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const tileServerURL = TILE_SERVERS[tileServer].url;
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if (tileServerURL.indexOf('{a-c}') !== -1) {
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TILE_SERVERS_ORIGINS.push(
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(new URL(tileServerURL.replace('{a-c}', 'a'))).origin,
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);
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TILE_SERVERS_ORIGINS.push(
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(new URL(tileServerURL.replace('{a-c}', 'b'))).origin,
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);
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TILE_SERVERS_ORIGINS.push(
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(new URL(tileServerURL.replace('{a-c}', 'c'))).origin,
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);
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} else {
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TILE_SERVERS_ORIGINS.push((new URL(tileServerURL)).origin);
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}
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});
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// Get duration (in s) before (cache) expiration from headers of a fetch
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// request.
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function getExpiresFromHeaders(headers) {
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// Try to use the Cache-Control header (and max-age)
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if (headers.get('cache-control')) {
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const maxAge = headers.get('cache-control').match(/max-age=(\d+)/);
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return parseInt(maxAge ? maxAge[1] : 0, 10);
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}
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// Otherwise try to get expiration duration from the Expires header
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if (headers.get('expires')) {
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return (
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parseInt(
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(new Date(headers.get('expires'))).getTime() / 1000,
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10,
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)
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- (new Date()).getTime()
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);
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}
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return null;
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}
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global.self.addEventListener('install', (event) => {
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DEBUG && console.log('SW: installing…');
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event.waitUntil(
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!DEBUG && global.caches.open(CACHE_NAME) // Don't cache during dev
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global.caches.open(CACHE_NAME) // Don't cache during dev
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.then((cache) => {
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DEBUG && console.log('SW: cache opened.');
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cache.addAll(assetsToCache).then(
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@ -61,14 +108,17 @@ global.self.addEventListener('fetch', (event) => {
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// Do not touch requests which are not GET
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if (request.method !== 'GET') {
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DEBUG && console.log(`SW: ignore non-GET request: ${request.method}`);
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DEBUG && console.log(`SW: ignore non-GET request: ${request.method}.`);
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return;
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}
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// Do not touch requests from a different origin
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// Only touch requests which we can cache or from tiles servers.
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const requestURL = new URL(request.url);
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if (ALLOW_CACHING_FROM.indexOf(requestURL.origin) === -1) {
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DEBUG && console.log(`SW: ignore different origin ${requestURL.origin}`);
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if (
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ALLOW_CACHING_FROM.indexOf(requestURL.origin) === -1
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&& TILE_SERVERS_ORIGINS.indexOf(requestURL.origin) === -1
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) {
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DEBUG && console.log(`SW: ignore different origin ${requestURL.origin}.`);
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return;
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}
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@ -76,28 +126,140 @@ global.self.addEventListener('fetch', (event) => {
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if (requestURL.pathname.startsWith('/api')) {
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// Note that if API is on a different location, it will be ignored by
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// the previous rule.
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DEBUG && console.log(`SW: ignore API call ${requestURL.pathname}`);
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DEBUG && console.log(`SW: ignore API call ${requestURL.pathname}.`);
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return;
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}
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// Serve tiles from cache or download and cache them
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if (TILE_SERVERS_ORIGINS.indexOf(requestURL.origin) !== -1) {
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event.respondWith(global.caches.open(`${CACHE_NAME}-tiles`).then(
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cache => cache.match(request).then(
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(response) => {
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// If there is a match from the cache
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if (response) {
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DEBUG && console.log(`SW: serving ${request.url} from cache.`);
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const expirationDate = Date.parse(response.headers.get('sw-cache-expires'));
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const now = new Date();
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// Check it is not already expired and return from the
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// cache
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if (expirationDate > now) {
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return response;
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}
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}
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// Otherwise, let's fetch it from the network
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DEBUG && console.log(`SW: no match in cache for ${request.url}, using network.`);
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return fetch(request.url).then((liveResponse) => {
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// Get tile caching duration from settings
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let tileCachingDurationPromise = (
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Promise.resolve(0) // no caching by default
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);
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if (
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localforage.driver() === localforage.INDEXEDDB
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) {
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tileCachingDurationPromise = loadDataFromStorage(
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'settings', 'tileCachingDuration',
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);
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}
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return tileCachingDurationPromise.then((tileCachingDuration) => {
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// This is caching duration from settings
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const cachingDuration = (
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tileCachingDuration || 0
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);
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// This is caching duration specified in HTTP headers
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const cachingDurationFromHeaders = getExpiresFromHeaders(
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liveResponse.headers,
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) || 0;
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// If any form of caching is possible, do it
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if (tileCachingDuration > 0 || cachingDurationFromHeaders > 0) {
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// Compute expires date from caching duration
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const expires = new Date();
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expires.setSeconds(
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expires.getSeconds()
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// Caching duration cannot be less than
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// specified by HTTP headers.
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+ Math.max(cachingDuration, cachingDurationFromHeaders),
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);
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// Recreate a Response object from scratch to put
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// it in the cache, with the extra header for
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// managing cache expiration.
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const cachedResponseFields = {
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status: liveResponse.status,
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statusText: liveResponse.statusText,
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headers: { 'SW-Cache-Expires': expires.toUTCString() },
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};
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liveResponse.headers.forEach((v, k) => {
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cachedResponseFields.headers[k] = v;
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});
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// We will consume body of the live response, so
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// clone it before to be able to return it
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// afterwards.
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const returnedResponse = liveResponse.clone();
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return liveResponse.blob().then((body) => {
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DEBUG && console.log(
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`SW: caching tiles ${request.url} until ${expires.toUTCString()}.`,
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);
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// Put the duplicated Response in the cache
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cache.put(request, new Response(body, cachedResponseFields));
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// Return the live response from the network
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return returnedResponse;
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});
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}
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// Otherwise, just return the live result from the network
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return liveResponse;
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});
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});
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},
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),
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));
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return;
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}
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// For the other requests, try to match it in the cache, otherwise do a
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// network call
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if (DEBUG) {
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// Never match from cache in production
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// Never match from cache in development
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return;
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}
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const resource = global.caches.open(CACHE_NAME).then(
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cache => cache.match(request).then(
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(response) => {
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if (response) {
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DEBUG && console.log(`SW: serving ${request.url} from cache`);
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DEBUG && console.log(`SW: serving ${request.url} from cache.`);
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return response;
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}
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DEBUG && console.log(`SW: no match in cache for ${request.url}, using network`);
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DEBUG && console.log(`SW: no match in cache for ${request.url}, using network.`);
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return fetch(request);
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},
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),
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);
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event.respondWith(resource);
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});
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global.self.addEventListener('message', (event) => {
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console.log(`SW: received message ${event.data}.`);
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const eventData = JSON.parse(event.data);
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// Clean tiles cache
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if (eventData.action === 'PURGE_EXPIRED_TILES') {
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DEBUG && console.log('SW: purging expired tiles from cache.');
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global.caches.open(`${CACHE_NAME}-tiles`).then(
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cache => cache.keys().then(
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keys => keys.forEach(
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key => cache.match(key).then((cachedResponse) => {
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const expirationDate = Date.parse(cachedResponse.headers.get('sw-cache-expires'));
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const now = new Date();
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// Check it is not already expired
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if (expirationDate < now) {
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DEBUG && console.log(`SW: purging (expired) tile ${key.url} from cache.`);
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cache.delete(key);
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}
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}),
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),
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),
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);
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}
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});
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