monorepo/kifu/pwa/src/sw.js

const CACHE_NAME = 'kifu-pwa-3';

self.addEventListener('install', event => {
    event.waitUntil((async () => {
        const cache = await caches.open(CACHE_NAME);
        cache.addAll([
            '/',
            '/kifu-bundle.js',
            '/kifu.css',
        ]);
    })());
});

self.addEventListener('fetch', event => {
    event.respondWith((async () => {
        const cache = await caches.open(CACHE_NAME);
        const cachedResponse = await cache.match(event.request);
        if (cachedResponse) {
            return cachedResponse;
        } else {
            try {
                const fetchResponse = await fetch(event.request);
                cache.put(event.request, fetchResponse.clone());
                return fetchResponse;
            } catch (e) {
            }
        }
    })());
});