Why multiple resources that explain the same concepts?
If you use different resources, you will be exposed to the concept in different context. This is especially useful for beginners to not stuck in one context. You need to understand the concept in different situation.
Also, feel free to modify the tutorial steps. Add in anything that is interesting. Apply previously learned knowledge to the tutorial. Combine two different concepts. In short, be active in experimenting.
One particular thing that is useful is the challenges that the course instructor gave to the students. After the instructor demonstrated on a practical concept, you are expected to complete the variant of the demo.
Disclaimer: I cannot give a complete review since I completed only the earlier chapters (1-7). In future, I will read the remaining chapters again.
forEach(..), filter(...) and map(...)) was useful later on when I studied with the other MOOCs.
I also advise beginners to try the few challenges that are available at the end of each chapters. I have consolidated my understanding by doing these challenges. Some of the challenges may be difficult. So you should feel free to refer to the code (this is not school).
The Complete React Developer Course
Food for Thought: React seems like a powerful framework that allows the application to process and compute data for the client side. Does this mean that more application will start perform business logic workflows in the client side and forgets about backend validation?