I think people coming from most other languages that have objects get very confused about prototypal inheritance. The significance of first-class functions is also not obvious to people who don't come from a functional programming background.

I think you're right insofar as it's easy to "get going" with JS and see things happen in a web page. But if you're looking to actually learn how to build non-trivial apps, a solid grounding in the language is pretty key.

9 books worth of grounding?

I think one beginner and one advanced book maybe. True, I did come from a different background than most (having learned both those features in other languages before ever doing javascript), but do you really need 7 more books to tell you about it?

I think the post is bordering on book affiliate spam.

I don't disagree with you on that point. Two books should be plenty. I'm only pointing out that there's a lot of utility in learning about JS as a programming language, completely divorced from DOM stuff.

That's because DOM interactions are one of the least interesting aspects of Javascript and not where the current innovation is happening. JQuery has pretty much taken care of that. Buy a JQuery book for that.

The newer javascript frameworks - the ones that are driving interest in Javascript as a language - are flexing the language features to the point where having good books help. The javascript language is pretty hard and strange when you really start getting in there.

No where on the page does it discount the normal case (using Javascript as page display and animation language) and point out these are mostly for the server side/complicated framework people.