ServiceWorkers (formerly Navigation Controllers) are a new system that provides event-driven scripts that run independent of web pages. They are similar to SharedWorkers except that their lifetime is different and they have access to domain-wide events such as network fetches. Use cases: offline, reducing perceived page load latency and will eventually power notification/push/sync/... use cases.
Docs: https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorker_API http://www.html5rocks.com/en/tutorials/service-worker/introduction/ http://jakearchibald.com/2014/using-serviceworker-today/
Samples: https://github.com/GoogleChrome/samples/tree/gh-pages/service-worker https://github.com/jakearchibald/trained-to-thrill