sw-download-install.js

const VERSION = 'v3';


self.addEventListener('install', event => event.waitUntil(installServiceWorker()));


async function installServiceWorker() {

    log("Service Worker installation started ");

    const cache = await caches.open(getCacheName());

    return cache.addAll([
        '/',
        'carousel.css',
        'http://getbootstrap.com/dist/css/bootstrap.min.css',
        'https://code.jquery.com/jquery-3.2.1.slim.min.js',
        'http://getbootstrap.com/assets/js/vendor/popper.min.js',
        'http://getbootstrap.com/dist/js/bootstrap.min.js',
        'http://getbootstrap.com/assets/js/vendor/holder.min.js'
    ]);
}

self.addEventListener('activate', () => activateSW());


async function activateSW() {

    log('Service Worker activated');

    const cacheKeys = await caches.keys();

    cacheKeys.forEach(cacheKey => {
        if (cacheKey !== getCacheName() ) {
            caches.delete(cacheKey);
        }
    });

}


self.addEventListener('fetch', event => event.respondWith(cacheThenNetwork(event)));



async function cacheThenNetwork(event) {

    const cache = await caches.open(getCacheName());

    const cachedResponse = await cache.match(event.request);

    if (cachedResponse) {
        log('Serving From Cache: ' + event.request.url);
        return cachedResponse;
    }

    const networkResponse = await fetch(event.request);

    log('Calling network: ' + event.request.url);

    return networkResponse;


}






function getCacheName() {
    return "app-cache-" + VERSION;
}


function log(message, ...data) {
    if (data.length > 0) {
        console.log(VERSION, message, data);
    }
    else {
        console.log(VERSION, message);
    }
}