As Service Worker is a progressive enhancement we can still use it even though Safari doesn't support it yet.
Safari still supports AppCache which SW is designed to replace (AppCache has some unfixable problems) so although it doesn't have the richness of SW it still has some declarative offline support
Safari still supports AppCache which SW is designed to replace (AppCache has some unfixable problems) so although it doesn't have the richness of SW it still has some declarative offline support