sw.js

const CACHE_NAME = 'clock-app-cache-v1';
const urlsToCache = [
    '/',
    '/index.html',
    '/manifest.json',
    '/sw.js',
    '/icons/icon-192.png'
];

self.addEventListener('install', event => {
    event.waitUntil(
        caches.open(CACHE_NAME)
        .then(cache => {
            console.log('Opened cache');
            return cache.addAll(urlsToCache);
        })
    );
});

self.addEventListener('fetch', event => {
    event.respondWith(
        caches.match(event.request)
        .then(response => {
            // 缓存命中
            if (response) {
                return response;
            }
            // 资源请求
            return fetch(event.request);
        })
    );
});

self.addEventListener('activate', event => {
    const cacheWhitelist = [CACHE_NAME];
    event.waitUntil(
        caches.keys().then(cacheNames => {
            return Promise.all(
                cacheNames.map(cacheName => {
                    if (!cacheWhitelist.includes(cacheName)) {
                        return caches.delete(cacheName);
                    }
                })
            );
        })
    );
});