I didn't gain much from this chapter, and I haven't decided if it is because it wasn't written well, I don't have sufficient background in parsing and JavaScript to appreciate it, or both. I wish the chapter started with a clearer explanation of what problem it was trying to solve and why other solutions are not beautiful. I could have also benefitted from some more background on Pratt parsing. I glanced at the referenced ACM paper, and it appears to be helpful (with a lot more study than I was interested in giving to it).
So, this comment is merely a placeholder for some better comments!
I was lost too when trying to figure out what the problem being solved was. I probably missed the point completely, but this chapter looked like syntax parser model and implementation. This may have been javascript parsing specific, but I didn't pick up on that at all. If I were going to write a programming language, I would go back to this chapter and use its patterns. I was focused on the functions and the parsing layers (or precedence) in a general sense, because I'm not very familiar with javascript.
So, this comment is merely a placeholder for some better comments!