I don't think you need to read so much to get going in JavaScript. If you already Node and Mongo, you already know quite a lot. Just getting more practice. And whenever you have any doubt, check with MDN (Mozilla Developer Network), and improve your knowledge over a period of time.
As a developer, I don't memorize syntax and names. I routinely search for them, though it takes time. Instead, I remember abstract concepts. What are the options to manage state in UI? How to design a good image picker or dropdown? etc.