For introduction, I recommend online courses cause they are easy to understand. To the next level, gorgeous books like The Good Parts can be a great help. Then we might be able to study the source code of popular frameworks and join or create Github projects. As frontend is developing too fast, no doubt frontend developers need to learn quickly and thoroughly. To be more effective, distinguishing and grasping the key content should go without saying.
For those BA girls who’s learning frontend like me:
Understand comes first. Practice more code. Focus on priorities. Keep a blog instead of literal notes. Look up documentation and stackoverflow for small points. Finally write your own code, keep up with the most popular technology and dig into your interest.
The most important skill is to solve the problems as fast as you could.