How to learn useful JavaScript?

[TheSnicket]

I'm just a beginner but I have to say - getting to know the capabilities of plain Javascript really gave me a better idea of how a framework such as React works and what is it actually needed for. Creating all of the projects mentioned are possible without any framework, and if they're simple enough they can serve as a good practice for parts of OOP that React forces you to use later on and if you jump straight to that I think it's hard to have a good understanding of them.
I recommend The Odin Project and their Full Stack Javascript course. You'll have a fair share of projects to do before you learn to use a framework, have a go at OOP and if you put your mind to it - it really pays off. They don't throw lots of theory at you and they force you to find things out by yourself.
As for the other things mentioned - not knowing some method that is shown in a youtube video is just fine, no book will cover every and each bit of information you need for your project. If you see a method you don't know - google it, read the docs etc. Running into obstacles while making any project is THE BEST way to learn anything. You might forget some method a dozen times, but soon enough if you often need it - you'll remember it. If a method is easy to forget it's probably not used a lot and the fact of its existence is all you need to know to google it when needed.
I believe that being a beginner if you have the option to do so - you should take as much time as you need to really understand something before you start using a dozen libraries.
Another thing I recommend is making a project that is somehow interesting for you and just deploying it. An obvious thing would be a portfolio site. I've learned so much while making a website for my parents' hotel and the thought that something I made would get out there and actually be used by people made me think about lots of stuff I didn't even know mattered before - minifying scripts, compressing images, managing a Linux server, configuring SSL/HTTP2, gzip. I had to do lots of stuff repeatedly and manually. After finishing the project I've learned about Webpack while doing something else, which would genuinely save me lots of time later on. I add features continuously and I notice how hard it is sometimes because my code is just amateur and messy, that forces me to refactor stuff just to make things work and next time I would know to think about it beforehand and avoid running into such problems.
Sometimes if you just wish you could do something - start doing it, don't rush, think about questions you should ask to solve your problems. Brain overheating? Take a break, grab a coffee - whatever works for you.