This service worker explicitly caches all the resources the app needs to run then intercepts requests for those resources so all the JS that depends on the resources still runs while you're offline.
If you had visited the site in the past, even if you were offline you would be able to go to that URL and the service worker would serve everything needed from cache.
This service worker explicitly caches all the resources the app needs to run then intercepts requests for those resources so all the JS that depends on the resources still runs while you're offline.
If you had visited the site in the past, even if you were offline you would be able to go to that URL and the service worker would serve everything needed from cache.