js6chars

Transform a JavaScript code into an equivalent JavaScript code using only 6 characters.

Project implementation hightly relies on ways web-browsers dysplay some datatypes. It is supposed to work under both Firefox and Google Chrome.

Nonetheless -c <positive number> should work on every browser.

How to use it?

js6chars makes it possible to convert JavaScript data into their equivalent versions using only a 6-character subset: []+()!

js6chars syntax:

-c <character> : string of one character
-n <number>    : number
-s <script>    : script
-t <text>      : string

Example:

:$ ./build/js6chars -c 0
 > +[]

How does it work?

Basic conversions in JavaScript

• conversion to Boolean: add ! in front of the data -- eg.: !1 === false
• conversion to Number: add + in front of the data -- eg.: +"3" === 3
• conversion to String: add +[] to dta -- eg.: undefined+[] === "undefined"

Trick by trick

• Numbers from 0 to 9:
• +[] === 0
• ++[[]][+[]] === 1
• ++[++[[]][+[]]][+[]] === 2
• ...
• ++[N][+[]] === N+1
• Numbers' string representation: ++[[]][+[]]+[] === "1"
• undefined: [][0] === undefined -- d,e,f,i,n,u
• [][+[]] === undefined
• [][+[]]+[] === "undefined"
• ([][+[]]+[])[+[]] === "u"...
• NaN === +("u") -- a,N
• 1e+308 === 1e308 -- +
• function find() { [native code] } === []["find"] -- c,o,t,v, ,(,),[,],{,}
• true === !![] -- r
• false === ![] -- l,s
• function Number() { [native code] } === (0).constructor === (0)["constructor"] -- b,m,r
• function Array() { [native code] } === (0).constructor === []["constructor"] -- y,A
• function String() { [native code] } === (0).constructor === ([]+[])["constructor"] -- g,S
• function Function() { [native code] } === (0).constructor === []["constructor"]["constructor"] -- F
• function Boolean() { [native code] } === (0).constructor === (![])["constructor"] -- B
• Characters from a to z
• "a" === 10["toString"](11)
• "b" === 11["toString"](12)
• ...
• "C" === Function("return atob(\"20N\")[1]")()
• All other characters: ([]+[])["constructor"]["fromCharCode"](\d+)

Sources

Project inspired by:

• http://slides.com/sylvainpv/xchars-js/
• https://syllab.fr/projets/experiments/sixcharsjs/