During my employeetime at inviqa i had good chances to do researches on a recent web technology. I started to prepare a presentation as a slidedeck and wrote a blog entry. Which is now authored by a former good colleague. I don't know why. But you can see my origin in the little debugging gif animation on the blog entry.
A Service Worker is a good technology partner to improve a websites performance and provide an offline experience for a returning visitor.
Progressive Web Apps do rely on.