Observable is one of the easiest platforms to get started with. JS is not the language I'd pick, but it's what runs in the browser so there we go.
I've tried to simplify things a lot for beginners, which comes with some technical inaccuracies, but there are probably some that need to be ironed out as well.
Still needs editing from a native speaker, but would love to hear feedback, suggestions for more topics, and any general experience about teaching programming to total beginners.