Workers will be at your service in an upcoming release of Safari — specifically Safari Technology Preview 48, macOS High Sierra 10.13.4 and iOS 11.3 beta seed 2.
Youenn Fablet, software engineer at Apple, writes:
While WebKit’s implementation and feature set is quickly evolving, we believe it has reached an important milestone in terms of functionality and compliance: applications using service workers for offline support or network/cache optimizations run successfully on latest WebKit builds. Let’s now dive into the specifics...
This news comes after Microsoft announces PWAs are coming to Microsoft Edge and Windows.