serviceWorker.js

const staticAssets = [
    '/index.html',
    '/css/main.css',
    '/js/app.js'
];

self.addEventListener('install', async event => {
    const cache = await caches.open('static-alismed');
    cache.addAll(staticAssets);
});

self.addEventListener('fetch', event => {
    //caching for offline viewing
    const {request} = event;
    const url = new URL(request.url);
    if(url.origin === location.origin) {
        event.respondWith(cacheData(request));
    } else {
        event.respondWith(networkFirst(request));
    }
});

async function cacheData(request) {
    const cachedResponse = await caches.match(request);
    return cachedResponse || fetch(request);
}

async function networkFirst(request) {
    const cache = await caches.open('dynamic-alismed');

    try {
        const response = await fetch(request);
        cache.put(request, response.clone());
        return response;
    } catch (error){
        return await cache.match(request);
    }
}