Offline Web Applications | Udacity
This is a free online video course recorded by Jake a couple of years back. It’s got a really good step-by-step introduction to service workers, delivered in Jake’s typically witty way. Some of the details are a bit out of date, and I must admit that I bailed when it got to IndexedDB, but I highly recommend giving this a go.
There’s also a free course on web accessibility I’m planning to check out.