I don't remember who said it, but javascript has been called "Scheme with Algol syntax". So for learning Scheme/Lisp, Javascript isn't a bad start. Note though that functional languages like Lisp are quite different from pure functional languages, such as Haskell.
Apart from "first-class functions" (Meaning that functions are values, that can be assigned to variables), lexical scope is also an inherent part of what makes a functional language.
Higher Order Javascript and The Little Javascripter has been mentioned already. They are both excellent texts. In addition, Higher Order Programming in Javascript may be an easier start.