What is this?

In browsers supporting Service Workers, in the Treasure Island web book and here, you'll see a checkbox enabling you to continue having a seamless reading experience even if you drop offline.

After you check that box, you’ll see a message saying Caching complete! This Web publication is now readable offline. (For the Treasure Island web book, it may take a while for the message to appear, depending on the speed of your Internet connection—it needs to cache about 109MB of content).

But once that …now readable offline message appears, turn off your WiFi, remove your Ethernet cable, or put your phone into Airplane Mode, and you’ll still be able to continue reading this content, at the same URL—just as if you were still online.

Continue to page 2 for more details about what this is demonstrating and in what way it uses Service Workers.

Credits: This is largely just a slightly-modified version of an earlier demo created by Jake Archibald.