The first is "Adaptive Web Design: Crafting Rich Experiences with Progressive Enhancement, 2nd Edition" by Aaron Gustafson. This is the greatest resource of "stuff they forgot to tell you" when you learn web development that I have ever seen in printed form.

The second is "Secrets of the Javascript Ninja" by Biebault and Resig. Every one of my devs groaned at first, then thanked me profusely when they finished it.

FWIW, my favorite "look-it-up"-style resource is Speaking Javascript by Rasuchmeyer - and his follow-up "Exploring ES6".