sw.js

/*
  self.addEventListener('install', function (event) {
    event.waitUntil(
        caches.open('sw-cache').then(function (cache) {
            return cache.add('sw.js');
            //return cache.add('index.html');
            //addAll({ array]);})
        })
    );
});

self.addEventListener('fetch', function (event) {
    event.respondWith(
        caches.match(event.request).then(function (response) {
            return fetch(event.request);
            //return response || fetch(event.request);
        })
    );
});
*/









// the cache version gets updated every time there is a new deployment
const CACHE_VERSION = 10;
const CURRENT_CACHE = `main-${CACHE_VERSION}`;

// these are the routes we are going to cache for offline support
//const cacheFiles = ['/', '/about-me/', '/projects/', '/offline/'];
const cacheFiles = [];

// on activation we clean up the previously registered service workers
self.addEventListener('activate', evt =>
    evt.waitUntil(
        caches.keys().then(cacheNames => {
            return Promise.all(
                cacheNames.map(cacheName => {
                    if (cacheName !== CURRENT_CACHE) {
                        return caches.delete(cacheName);
                    }
                })
            );
        })
    )
);

// on install we download the routes we want to cache for offline
self.addEventListener('install', evt =>
    evt.waitUntil(
        caches.open(CURRENT_CACHE).then(cache => {
            return cache.addAll(cacheFiles);
        })
    )
);

// fetch the resource from the network
const fromNetwork = (request, timeout) =>
    new Promise((fulfill, reject) => {
        const timeoutId = setTimeout(reject, timeout);
        fetch(request).then(response => {
            clearTimeout(timeoutId);
            fulfill(response);
            update(request);
        }, reject);
    });

// fetch the resource from the browser cache
const fromCache = request =>
    caches
        .open(CURRENT_CACHE)
        .then(cache =>
            cache
                .match(request)
                .then(matching => matching || cache.match('/offline/'))
        );

// cache the current page to make it available for offline
//const update = request =>
//    caches
//        .open(CURRENT_CACHE)
//        .then(cache =>
//            fetch(request).then(response => cache.put(request, response))
//        );
const update = request => { };
// general strategy when making a request (eg if online try to fetch it
// from the network with a timeout, if something fails serve from cache)
self.addEventListener('fetch', evt => {
    evt.respondWith(
        fromNetwork(evt.request, 10000).catch(() => fromCache(evt.request))
    );
    evt.waitUntil(update(evt.request));
});