What's a good way to learn IndexedDB client-side storage?

So you have a small amount of data you want to store client-side using the IndexedDB API but you're not quite sure how it works.

I've found this simple notes app example (scroll halfway down the page) to be a great way to get some hands-on practice using IndexedDB.

The MDN docs state that if you have a lot of data you should always just use a dedicated database like MongoDB but I can see how using IndexedDB can come help speed up your application by reducing the need to constantly pull data from the database everytime a visitor comes back to the app.