Mobx is really nice. For a quick and easy database for an Electron app I added a Mobx observer that persists the state to a json file which is read back at startup. It was just a few lines of code and you get seemless persistence for free.

I've expanded on that idea for another Electron app I'm working on (http://www.serverwrangler.com) that encrypts the data before saving and has a database "server" in the main process so data is shared between multiple Electron windows of the same app.