19 November 2019 The  Service Workers Working Group  has published a Candidate Recommendation of  Service Workers 1 . This specification describes a method that enables applications to take advantage of persistent background processing, including hooks to enable bootstrapping of web applications while offline. The core of this system is an event-driven  Web Worker , which responds to events dispatched from documents and other sources. A system for managing installation, versions, and upgrades is provided. The service worker is a generic entry point for event-driven background processing in the Web Platform that is  extensible by other specifications . Comments are welcome by  31 January 2020 .