[hpvic03]

To persist data you'll want a backend. That's a fairly important piece of any application which is why I included it in the tutorial. You could ignore the Rails parts of the tutorial and create your own backend.

[pyre]

Persist across clients, maybe, but it's also possible to use localStorage to persist data on a single client.

[TheBrockEllis]

You could also use something like Firebase as a datastore that could persist across multiple clients but also be implemented in javascript.