Progressive Web Application Development by Example

How the service worker cache works

The service worker sits between the browser and the network. By adding a fetch event handler, you can determine how the request is handled. All network requests pass through the service worker's fetch event handler:

This gives you a hook, or way to inject logic into the workflow, to intercept requests and determine how and where the response is returned.

With the service worker, you can do the following:

• Pass the request to the network, the traditional method
• Return a cached response, bypassing the network altogether
• Create a custom response

When the network fails, you can program the service worker to ...