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.
Service Workers are now under active development in MS Edge. You can track progress at https://developer.microsoft.com/en-us/microsoft-edge/platform/status/serviceworker
The most important new feature needed for web applications
Ege Özcan commented
Service Workers are *essential* for making reliable, high-performance offline applications. Unless we have a miracle happening in the connectivity world, enabling high-bandwidth data access for cheap anywhere in the world, lack of Service Workers is a show-stopper for various kind of offline apps. No, HTML appcache doesn't cover most cases.
Matheus Kautzmann commented
The Service Worker spec will empower the creation of new and better offline apps. Please support it.
Any updates here?
Šime Vidas commented
The title of this entry should be amended with “(mother effing OFFLINE web apps)” to make it absolutely clear what this is.