I came here to write this exactly. This looks like a nice resource, the tone is friendly and inviting and the topics are introduced at a nice pace. Then I thought about my cousin who I've been trying to teach to program a bit. She's interested and she's smart, she understands how things work at a conceptual level and she can design an algorithm. But if I just give her some JS and ask her to run it she'll stare blankly right back at me.

The introduction needs to talk about prerequisites, setting up for following along way before getting into the topics. Right now it's just a (broken) link to the appendix, which I don't think is good enough.

I like this overall though, it's good stuff. I'm going to try and find some time for a PR to change the introduction into something I think would be better for a newbie, and if translations are welcome I might just work on a Swedish version.