Rather than writing a poorly written basic tutorial here, I'll link to some key resources. After all, you're the one who knows how deep your understanding of Service Workers is.
The MDN documentation is a great place to learn more about Service Workers and their capabilities. If you're already confident with the basics of web development and enjoy a learn-by-doing approach, I highly armenia mobile database recommend completing Google's PWA training course . It includes an entire hands-on exercise on Service Workers , which is a great way to get familiar with the basics. If ES6 and promises aren't already part of your JavaScript repertoire, prepare for a baptism of fire.
The key thing to understand—and you’ll quickly realize once you start trying it—is that service workers put an incredible amount of control in the hands of the developer. Unlike previous attempts to solve connectivity challenges like the ill-fated AppCache , Service Workers don’t enforce any particular pattern on your work; they’re a set of tools for you to write your own solutions to the problems you face.