Rule 34 for software: If it exists, there IS a javascript port of it.
http://www.codinghorror.com/blog/2007/07/the-principle-of-le...
And tlrobinson's Law (or corollary?): Any submission to Hacker News about a novel JavaScript program will contain a comment referencing Atwood's Law.
http://www.emacswiki.org/emacs-fr/Ejacs
Ejacs is an Ecma-262 compliant JavaScript interpreter written entirely in Emacs Lisp. It should work in GNU Emacs versions 22 and higher.
;-)