There are two JS courses on Codecademy, which are good to take.
(There are also other courses that are relevant, such as jQuery and React for example.)
Eloquent is a little more advanced, but if you can go through that and successfully get through the exercises without help, you'll have grasped some good understanding of the JS concepts.
The final step is Node.JS. If you really want to become fluent in JS, take these steps one at a time and build up your knowledge.
Thank you! Exactly the kind of guidance I was looking for. I'll check out all of those resources.