You are probably mistaken SW for Web Workers. Web Workers are used to offload work to another thread and can communicate with messages Service Workers is a ne

You are probably mistaken SW for Web Workers. Web Workers are used to offload work to another thread and can communicate with messages Service Workers is a new API which is now supported by all major browsers. SW is branded as: Rich offline experiences, periodic background syncs, push notifications and more. "A service worker is a script that your browser runs in the background, separate from a web page, opening the door to features that don't need a web page or user interaction." Full article on this topic: https://developers.google.com/web/fundamentals/primers/service-workers/ https://developers.google.com/web/fundamentals/primers/servi...