Caching
One of the most important progressive web application features is the ability to work offline and load instantly. Service worker caching enables this super power. In the past, websites could function offline and even gain some performance benefits via appCache.
Service worker caching supersedes appCache and provides a better programmatic interface. AppCache is notorious for being difficult to manage and maintain.
When your page references an appCache manifest file and has a registered service worker, the service worker manages cache and the appCache is bypassed. This makes service worker caching a progressive enhancement from appCache and makes it safe to use both.
By enabling caching, service workers make the network a progressive enhancement. Because the service worker cache API is very low level, it requires the developer to apply custom logic to manage how network resources are cached and retrieved.
This leaves lots of room for creativity to apply different caching strategies in...
