sw.js

var dataCacheName = 'v1';
var cacheName = 'v1';
var filesToCache = [
   "./index.html", "./code.js", "./css/heroic-features.css"
];

self.addEventListener('install', function (e) {
    console.log('[ServiceWorker] Install');
    e.waitUntil(
        caches.open(cacheName).then(function (cache) {
            console.log('[ServiceWorker] Caching app shell');
            return cache.addAll(filesToCache);
        })
    );
});

self.addEventListener('activate', function (e) {
    console.log('[ServiceWorker] Activate');
    e.waitUntil(
        caches.keys().then(function (keyList) {
            return Promise.all(keyList.map(function (key) {
                if (key !== cacheName && key !== dataCacheName) {
                    console.log('[ServiceWorker] Removing old cache', key);
                    return caches.delete(key);
                }
            }));
        })
    );

    return self.clients.claim();
});

self.addEventListener('fetch', function (e) {
    console.log('[Service Worker] Fetch', e.request.url);
    var dataUrl = 'https://machadoastur.github.io/';
    if (e.request.url.indexOf(dataUrl) > -1) {
        /*
         * When the request URL contains dataUrl, the app is asking for fresh
         * weather data. In this case, the service worker always goes to the
         * network and then caches the response. This is called the "Cache then
         * network" strategy:
         * https://jakearchibald.com/2014/offline-cookbook/#cache-then-network
         */
        e.respondWith(
            caches.open(dataCacheName).then(function (cache) {
                return fetch(e.request).then(function (response) {
                    cache.put(e.request.url, response.clone());
                    return response;
                });
            })
        );
    } else {
        /*
         * The app is asking for app shell files. In this scenario the app uses the
         * "Cache, falling back to the network" offline strategy:
         * https://jakearchibald.com/2014/offline-cookbook/#cache-falling-back-to-network
         */
        e.respondWith(
            caches.match(e.request).then(function (response) {
                return response || fetch(e.request);
            })
        );
    }
});