A service worker is a type of worker (JavaScript application) installed in the browser that can act as a forward proxy.
They can:
They can receive http requests (and associated resources) created by the server
They make the following feature possible in the browser:
This section explains the http cache feature.
The first time a user visits your page using a browser that supports service worker, all of the resources needed to use the page offline can be automatically cached locally, and each subsequent visit to any page on the site will be:
The service worker needs to be registered (associated with) against:
sw-toolbox and sw-precache are deprecated in favor of Workbox.