Write any JavaScript with 6 Characters

JSFuck is an esoteric, educational style of JavaScript that uses only six different characters, (, ), +, [, ], and !, to write and execute code. It does not depend on a browser, so it can run on Node.js. The page includes a form for converting user scripts, with an option to uncheck "eval source" to get back a plain string. It also lists alternatives, including Hieroglyphy (8 characters, browser only), and notes that utf-8.jp and JS-NoAlnum are broken. The project is credited to Martin Kleppe (@aemkei), with the original discussion held at Sla.ckers.org.