EDIT I gave my advice for a junior dev, not a junior QA engineer, but titles are titles, you asked about “developer” questions, so I assume you plan on becoming a software engineer/ developer down the line
There is one “go-to” reference for design patterns. It is old, but the patterns still apply today. The best way to really learn them is to implement them in a programming setting, so its not just “concepts”.
Learn about things like multi-threading
You will need to probably learn a new language to learn this subject, as JS is single threaded. If you are really interested about this topic and what it means for JS, and other langauges then go ahead and dive into any other general programming language you’d like to learn aswell. Otherwise, just understand JS is single threaded, which means don’t block the event loop.
When to use which data-type in case of dealing with very large volumes
Not sure what you mean by this question. If we are talking about JS, and actual large amounts of data, the data-type your dealing with is kind of an after thought, streams come to mind as a way to handle large amounts of data without taking up all your ram, but idk if you’d call this a “data-type”.
How to query data efficiently in SQL
The best way to learn SQL is to learn database design, and the syntax to get the data you want/need. You can always query around a well designed database without much trouble, but if its designed inefficiently, or straight up wrong, you will probably have more trouble. Just don’t get the concepts mixed up with the syntax, each database management software (MYSQL, MSSQL, etc) has their own quirks, but the database design concepts are always the same.
If you plan on going full-stack, then building a full-stack app is a good idea to cover lots of areas you may want to learn, strengthen you “general” JS skills, and learn the different levels of tech you will end up using as a full stack dev.
If your going to focus on the client-side, then I’d say general programming and design patterns are the most important (out of what you brought up) to focus on.
If your going mainly back-end, I’d recommend picking up another popular back-end language, and still look into all of the points you mentioned.