I went to khanacademy.org. they teach JS. I want to learn C#...
Since you're already in C++/Python classes. I recommend focusing on learning how to program in those languages. Once you understand some basic concepts, just start messing around with game development things like moving something around on the screen. If you'd rather focus on Python, search for Pygame tutorials. If you'd rather focus on C++, look into the Unreal engine and associated tutorials.
In the early part of your career, it's better to focus on a language while you learn how to program. Later on, picking up multiple languages is pretty easy so which one you choose first isn't as important as figuring out how to code games.