cobalt/worker/testdata/service_worker.js

self.addEventListener('install', function (event) {
  event.waitUntil(
    caches.open('v1').then(function (cache) {
      console.log("cache", cache);
      return cache.addAll([
        '/testdata/',
        '/testdata/service_worker.html',
        '/testdata/google_logo.png',
      ]);
    })
  );
});

self.addEventListener('fetch', function (event) {
  event.respondWith(caches.match(event.request).then(function (response) {
    if (response !== undefined) {
      return response;
    } else {
      return fetch(event.request).then(function (response) {
        let responseClone = response.clone();

        caches.open('v1').then(function (cache) {
          cache.put(event.request, responseClone);
        });
        return response;
      });
    }
  }));
});