ejacs - Google Code
http://code.google.com/p/ejacs/

Ejacs is an Ecma-262 compliant JavaScript interpreter written entirely in Emacs Lisp. It should work in GNU Emacs versions 22 and higher.

Ejacs is an Ecma-262 compliant JavaScript interpreter written entirely in Emacs Lisp

JavaScript in emacs

ELispで書かれたEcma-262 インタプリタ。Emacs22以降で動くらしい

emacsでjsインタプリタ。alertとかDocument.writeとかが使えないから微妙