Does someone know if there are some good exercises on these things?

Answer 1

The lessons that they do are very food for beginners and are good refreshers for intermidiate and advanced coders etc.

The challenge games they do on the mobile app are good fun, help with remembering and learning. So far I've only done the JS one, which I found tends to spend too much time asking questions that rely on math skill as opposed to testing you JS knowledge.