3 reasons to use service workers
1 Offline support
The headline feature of service workers is that they allow you to build pages that work offline and with intermittent network connection, by serving up content from a browser cache in the manner of your choosing.
Nobody likes waiting for a page to load. Loading content from a cache is nearly instantaneous, and because you can control caching at a granular level, service workers allow you to take advantage of this without risking showing stale data.
3 Native features
Because they run in the background, service workers let you do things you take for granted in native apps but couldn’t previously do on the web. Push notifications and background synchronisation are two examples of this.