Don’t learn how to use frameworks. It’s a knowledge that will expire fast. On the other hand, you should learn how frameworks work, that is very valuable knowledge.
- Learn the merits of functional programming and use its concepts where you can. Learn how to be declarative instead of imperative when you can.
- Learn small libraries like React and Redux which do one thing and do it well. Pick libraries with the smallest API.
- Learn how to build scalable data APIs (take a look at GraphQL)
Cutting Edge - ASP.NET Core for ASP.NET Developers
Cutting Edge - Guidelines for ASP.NET MVC Core Views