In general, for me at least i find the best way to learn about something is to work in the 'internals'. For instance when react came i couldn't wrap my head around it so i started my own js framework, and it ended up almost exactly like react (then i dumped it as it ended up just being a learning exercise)
I'm trying to become a top 0.01% JS user and creating linters, flavors, etc is my plan as well. I've read through and annotated the React codebase but it didn't stick very well. I would have done better to create my own framework! I keep having to relearn that lesson... I can have a lot of knowledge about a thing through reading, but knowledge of the thing requires some practical application.
A tangent, but as it relates to that, if anyone reading has ideas on how to apply traditional computer science curriculum, I would love to hear it. I can think of toy CPU emulators, system architecture diagramming, language creation... But not sure if there's a thing I can build that would say, "I understand computer science."