What is a service worker, and what role does it play in making an Angular app work offline?

A service worker is a script that runs separately from your app in the background, intercepting network requests and deciding whether to serve a cached response or fetch a fresh one from the network. Angular's built in service worker automatically caches your app's files, letting the app continue loading and functioning even without an internet connection.

// ngsw-config.json controls what the service worker caches
{
  "assetGroups": [
    { "name": "app", "installMode": "prefetch", "resources": { "files": ["/*.js", "/*.css"] } }
  ]
}