I have written and maintained very few scripts and it was a frustrating experience to have them working on several browsers.
I wanted a concise book about writing simple and maintainable code. I also wanted to learn more about the weird syntax constructions spotted when reading non-trivial bits of code, such as processing.js or CouchDB View's map/reduce.
This is exactly the kind of book I'm looking forward to when learning a programming language. It is short (100 pages + 50 pages of appendixes including JSON description) but dense, the sample code are small and meaningful (even the done to death
factorial functions used here to explain memoization).
The book does not lose space describing extensively the whole language. It focuses on the subset which is good and proven and do not talk about the edges or the parts which are better forgotten. It really shows how to write code which is both readable, maintainable and elegant.