FWIW, I'm an experienced developer without JS knowledge, but I decided it was time to write a Firefox extension, and I needed to finally learn JS. I chose "Modern JavaScript for the Impatient" (Horstmann) because its target audience is developers coming from other languages. He mentions Corckford's book, and says

"Crockford’s JavaScript: The Good Parts2 was a wake-up call in 2008, but much of its message has been internalized in subsequent changes to the language."

And the Rhino book is too large for what I need to accomplish.