A new Angular Service Worker — creating automatic progressive web apps. Part 1: theory
https://medium.com/progressive-web-apps/a-new-angular-service-worker-creating-automatic-progressive-web-apps-part-1-theory-37d7d7647cc7

A new Angular Service Worker — creating automatic progressive web apps. Part 2: practice
https://medium.com/google-developer-experts/a-new-angular-service-worker-creating-automatic-progressive-web-apps-part-2-practice-3221471269a1