To me, the nice part of JS is that you can get pretty far without knowing the language intricately. So you can actually get started and be somewhat productive while picking up more knowledge along the way. The front-end ecosystem is so broad that it's hard to focus only on vanilla JS anyway.

That said, if you want a comprehensive read about Javascript, there's You don't know JS: https://github.com/getify/You-Dont-Know-JS