That doesn't explain why choose it from among the majority of other languages that aren't centered on classes. JavaScript is so quirky, it seems like a really strange choice for a general programming book.
Perhaps it's my back end bias showing.
I feel its better to reach more developers, than aim for the best technologies that very few are actually even aware of.
I'm sure the author had his reasons, and there are certainly worse choices in the top dozen languages. (Refactoring... in PHP!)
> Such a language needed to be widely popular, among the top half a dozen in language popularity surveys. It really helps to have a C-based syntax, since most programmers would recognize the basic code structure
You can argue others, but at least this will help you understand why he chose it over many other languages that aren't centered on classes.