awesome-wm-widgets/assets/js/service-worker.js

const CACHE_NAME = 'awmw-cache';
const PRE_CACHED_ASSETS = [
    '/assets/css/materialize.min.css',
    '/assets/css/style.css',
    '/assets/css/syntax1.css',
    '/assets/js/materialize.min.js',
    '/assets/js/particles.min.js',
    '/assets/js/init.js',
    '/index.html'
];

self.addEventListener('install', function(event) {
    event.waitUntil(
        caches.open(CACHE_NAME).then(function(cache) {
            let cachePromises = PRE_CACHED_ASSETS.map(function(asset) {
                var url = new URL(asset, location.href);
                var request = new Request(url);
                return fetch(request).then(function(response) {
                    return cache.put(asset, response);
                });
            });

            return Promise.all(cachePromises);
        })
    );
});

self.addEventListener('activate', function(event) {
    event.waitUntil(
        caches.keys().then(function(cacheNames) {
            return Promise.all(
                // delete old caches
                cacheNames.map(function(cacheName) {
                    if (cacheName !== CACHE_NAME) {
                        return caches.delete(cacheName);
                    }
                })
            );
        })
    );
});

self.addEventListener('fetch', function(event) {
    if (event.request.headers.get('accept').startsWith('text/html')) {
        event.respondWith(
            fetch(event.request).catch(error => {
                return caches.match('index.html');
            })
        );
    }
});