[maxxxxx]

I don't think it's about learning new stuff. Find a really hard problem and work through it. That's how I learned the most. I am not talking about one month projects but something that takes a year or more. In a project of that size a lot mistakes you made at first come back to you over time and you can improve.

My most difficult projects have been done with C++ and took years. That experience still gives me an advantage even with JavaScript because I have developed pretty good instinct about what probably will work or not.