in see also on this page you list some other websites to learn from. Is anyone familiar with Grasshopper and is it any good?

I have used grasshopper before and I’m not the biggest fan, I feel like it moves way too fast and doesn’t make sure you fully understand a concept before introducing something else.
Each topic basically gives you one example with a screenshot for reference and doesn’t go into depth whatsoever, so although you may be able to solve the example problems, I find it difficult to retain alot of the information fed to me through grasshopper.
I myself use MDN mainly with some other free websites to supplement what I’m learning on here. I would suggest:

Code Academy
Free Code Camp