I’ve been playing around with ServiceWorker a lot recently, so when Chris asked me to write an article about it I couldn’t have been more thrilled. ServiceWorker is the most impactful modern web technology since Ajax. It’s an API that lives inside the browser and sits between your web pages and your application servers. Once installed and activated, a ServiceWorker can programmatically determine how to respond to requests for resources from your origin, even when the browser is offline. ServiceWorker can be used to power the so-called "Offline First" web.
ServiceWorker is a progressive technology, and in this article, I'll show you how to take a website and make it available offline for humans who are using a modern browser while leaving humans with unsupported browsers unaffected.