Recommended resources for learning advanced JavaScript

So I've been learning Javascript for a couple of years now and I feel more and more that my poor understanding of how it works under the hood is holding me back.

So I'm looking for resources that focus on how Javascript works under the hood. I'm thinking concepts such as execution context, event loop, scope, etc..

Preferably the resources contain a lot of examples and exercises for practice.

I've been following the guide on Javascript.info which is great, but I'm looking for something that goes even deeper than that. I've tried reading the "official" specification but it's just too dense for my brain to grasp.

So I would love to hear if anyone here has any such resources to recommend.