Well done, I like it. Stopped at the strings part though, because it introduces "let" and I still write and prefer ecmascript 5.1. Not for MSIE, but because the spec is much less to print and can much more easily fit in my brain. It's quite nicely done for those who want the modern JS, though.

Suggestion: it asks for a GitHub login twice, but only requires it once. Perhaps it could remember having signed in already?

How does `let` take up more space in your brain than `var`? I mean, write what you want to write, but the finger-wagging is bizarre. We're not talking about a new language feature here.

Thanks! Weird, it shouldn't ask for GitHub login twice. When was the second time that it asked? Was that maybe on the flashcards app?

Yes, I think it was indeed the flashcards part.

Not a fan of price hiding, could be included in the intro. https://learnjavascript.online/pay.html