Consider

[lemanschik]

• right place to apply import maps if any
• serviceWorker that uses import()

[lemanschik]

workbox.routing.registerRoute(
  new RegExp('^https://third-party.example.com/images/'),
  new workbox.strategies.CacheFirst({
    cacheName: 'image-cache',
    plugins: [
      new workbox.cacheableResponse.Plugin({
        statuses: [0, 200],
      })
    ]
  })
);

same as

var CACHE_NAME = 'monaco-editor-cache-v1';
var urlsToPrefetch = [
  '/',
  '/styles/main.css',
  '/script/main.js',
  'https://github.com/monaco-editor/.......'
];

self.addEventListener('install', function(event) {
  // Perform install steps
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(function(cache) {
        console.log('Opened cache');
        // Magic is here. Look the  mode: 'no-cors' part.
        cache.addAll(urlsToPrefetch.map(function(urlToPrefetch) {
           return new Request(urlToPrefetch, { mode: 'no-cors' });
        })).then(function() {
          console.log('All resources have been fetched and cached.');
        });
      })
  );
});