Dan Abramov - Facebook - This person is like the face of the React team, and he is a super nice down-to-earth Russian who admits he only knows JS but he knows it well. Awesome explanations on his blog.
Eric Elliot - He is the author of a number of great JS books. I'll link his blog down below.
Kyle Simpson - author of "you don't know JS". He has some great resources, but is also strongly opinionated on JS.
Advanced React Patterns - Kent C Dodds - Kent is the guy for React. Such a beast. These patterns I use heaps at wrork. I think he has a gentler intro course on FE masters too! Any of them are good.
React Docs - similar to "Rails Guides" being the source of truth, it is nice just to reference these often (add it to Dash if you use it) or even just read through once over at some stage just to get an idea of what is possible.
Utility Types - I always come here jsut to use some of the utilities for TS.
Mostly Adequate Guide to FP - this is funtional programming in JS and probably out of scope, but this book really help me translate a lot of FP jargon into real-world use and made reading the docs for Dry-Rb monads super easy.
Eric Elliot's Blog - this guy has a bunch of gems. Some of them go into the depths of JS in ways you won't need, so just be wary.
Frontend Masters - in general, Frontend Masters is the best resources for video tutorials. A bunch of the biggest names are there.
JS - The Hard Parts - this video course taught me a shitload. The guy is probably the best teacher I have seen when it comes to explaining the JS runtime, the importance of closures in JS and how queueing works for asynchronous JS in the Web and Node.js.