My go to for people new to JS.
Suffice to say once I hit that section I went back to codeacademy finished the course (which never brought them up and I'm not sure if that's good or bad) now I'm back in Eloquent Javascript...it get's really hard really fast.
The examples in Eloquent Javascript need to be studied by the reader to get the most out of that book. I think people just glance at them with out typing them up and running them.
I like the book "The Little Schemer" to learn recursion. Yes, a whole book to learn something other books briefly throw at you. You will not regret the read.