The book is primarily good at introducing the basic concepts of functional programming. It’s also one of the best for that in my opinion.
You wouldn’t use the quicksort from your textbook in production because it’s an example designed to teach specific principles. A complete tour of the literature on just that one story and all its variants and implications be a decent sized book all by itself.
Likewise, the examples inJS Allonge are vehicles to explore functional concepts.
I’d also note that there’s a PDF available for free.