dwsyoyo / jscrewit

Write any JavaScript with 6 Characters: []()!+

JScrewIt

JScrewIt converts plain JavaScript into JSFuck code, which uses only six different characters to write and execute any code: []()!+.

JScrewIt is a fork of JSFuck with the ability to optimize code for a particular set of JavaScript engines and even just for your browser.

The more specific your engine choice, the shorter the code you'll get.

Demo: jscrew.it

Example

The following source will do an alert(1) in any browser, including Internet Explorer:

[][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+
(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]][(+(+!![]+[+([][(![]+[])[+[]]+([![]]+
[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]
]+(!![]+[])[+!![]]]+[])[+[]]])+[!![]]+[][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]
]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]
])[+!![]+[+[]]]+(!!(+([][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]
+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]]+[])[+[]]+!![])
+[][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]
+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]])[+!![]+[+!![]]]+([][[]]+[])[+!![]]+
(![]+[])[!![]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+(+(+!!
[]+[+([][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])
[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]]+[])[+[]]])+[!![]]+[][(![]+[])[
+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!!
[]+!![]+!![]]+(!![]+[])[+!![]]])[+!![]+[+[]]]+(!![]+[])[+[]]+(!!(+([][(![]+[])[+
[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![
]+!![]+!![]]+(!![]+[])[+!![]]]+[])[+[]]+!![])+[][(![]+[])[+[]]+([![]]+[][[]])[+!
![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[]
)[+!![]]])[+!![]+[+!![]]]+(!![]+[])[+!![]]]((![]+[])[+!![]]+(![]+[])[!![]+!![]]+
(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]+(!!(+([][(![]+[])[+[]]
+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!
![]+!![]]+(!![]+[])[+!![]]]+[])[+[]]+!![])+[][(![]+[])[+[]]+([![]]+[][[]])[+!![]
+[+[]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+
!![]]])[!![]+!![]+[+[]]]+[+!![]]+(!!(+([][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[
]]]+(![]+[])[!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]
]]+[])[+[]]+!![])+[][(![]+[])[+[]]+([![]]+[][[]])[+!![]+[+[]]]+(![]+[])[!![]+!![
]]+(!![]+[])[+[]]+(!![]+[])[!![]+!![]+!![]]+(!![]+[])[+!![]]])[!![]+!![]+[+!![]]
])()

Usage

Installation

To use JScrewIt in your project, download [jscrewit.js] (https://github.com/fasttime/JScrewIt/blob/master/lib/jscrewit.js) or [jscrewit.min.js] (https://github.com/fasttime/JScrewIt/blob/master/lib/jscrewit.min.js) from GitHub and include it in your HTML file.

<script src="jscrewit.js"></script>

Alternatively, you can hotlink the online file.

<script src="https://rawgithub.com/fasttime/JScrewIt/master/lib/jscrewit.min.js"></script>

If you are using Node.js, you can install JScrewIt with npm.

npm install jscrewit

Then you can include it in your code.

var JScrewIt = require("jscrewit");

Encoding

Basics

This will encode the alert(1) example shown above and run it using eval.

var output = JScrewIt.encode("alert(1)", true);
eval(output);

The true passed as a second parameter indicates that we would like the output to be executable.

This parameter should be false to encode a plain string rather than JavaScript code.

var output = JScrewIt.encode("Hello, world!", false);
var input = eval(output); // input contains the string "Hello, world!".

Features

JScrewIt has the ability to generate JSFuck code that is targeted for a particular set of JavaScript engines (web browsers or Node.js). This optimized code is shorter than generic JSFuck code but does not work everywhere. To make use of this optimization, you have to specify which features the decoder engine is expected to support. In order to understand how this works consider the JavaScript functions atob and btoa. Not all browsers support these functions: without any further information, JScrewIt will assume that they are unavailable and will not be able to use them in generated code. Anyway, if you know in advance that the browsers you plan to target do support atob and btoa indeed, you can let JScrewIt create code that uses those functions whenever this would make the output shorter. The way to tell JScrewIt to use these features is by specifying a string (or array of strings) as a third parameter to encode.

For instance, the generic alert(1) example is 2084 chracters long.

var output = JScrewIt.encode("alert(1)", true); // output is 2084 characters

But if we specify that we are only interested in code that runs in an up to date Firefox browser, the output length shrinks to less than a half:

var output = JScrewIt.encode("alert(1)", true, "FF31"); // 972 characters now

You can specify more than one feature using an array, e.g.

var input = "document.body.style.background='red'";
var features = ["ATOB", "WINDOW"];
var output = JScrewIt.encode(input, true, features);

This table lists individual features of some common browsers.

Target	Features
Firefox 30+	ATOB ENTRIES (implied by NO_SAFARI_ARRAY_ITERATOR) FF_SAFARI_SRC FILL (Firefox 31+) GMT NAME NO_IE_SRC (implied by FF_SAFARI_SRC) NO_SAFARI_ARRAY_ITERATOR NO_SAFARI_LF QUOTE SELF (implied by WINDOW) UNDEFINED WINDOW
Google Chrome 35+, Opera 22+	ATOB ENTRIES (implied by NO_SAFARI_ARRAY_ITERATOR; Chrome 38+, Opera 25+) GMT NAME NO_IE_SRC (implied by V8_SRC) NO_SAFARI_ARRAY_ITERATOR (Chrome 38+, Opera 25+) NO_SAFARI_LF SELF (implied by WINDOW) UNDEFINED V8_SRC WINDOW
Internet Explorer 9+	ATOB (Internet Explorer 10+) GMT (Internet Explorer 11) IE_SRC NO_SAFARI_LF SELF (implied by WINDOW) UNDEFINED WINDOW
Safari 7.0+	ATOB ENTRIES (implied by SAFARI_ARRAY_ITERATOR; Safari 7.1+) FF_SAFARI_SRC FILL (Safari 7.1+) GMT NAME NO_IE_SRC (implied by FF_SAFARI_SRC) SAFARI_ARRAY_ITERATOR (Safari 7.1+) SELF (implied by WINDOW) UNDEFINED WINDOW
Android Browser 4.0+	ATOB DOMWINDOW (not in Android Browser 4.4.2+) GMT NAME NO_IE_SRC (implied by V8_SRC) NO_SAFARI_LF SELF (implied by DOMWINDOW and WINDOW) UNDEFINED (Android Browser 4.1.2+) V8_SRC WINDOW (Android Browser 4.4.2+)
Node.js 0.10.28+	GMT NAME NO_IE_SRC (implied by V8_SRC) NO_SAFARI_LF UNDEFINED V8_SRC

Keep in mind that each of the target engines needs to support every feature you specify. So if you want your JSFuck code to run on both Internet Explorer and Firefox, this won't work.

var features = ["IE9", "FF31"];

Instead, you have to specify features supported by both browsers. Those turn out out to be "NO_SAFARI_LF", "SELF", "UNDEFINED" and "WINDOW".

var features = ["NO_SAFARI_LF", "SELF", "UNDEFINED", "WINDOW"];

Reference

JScrewIt.areFeaturesAvailable(features)

Returns true if all of the specified features are available in the current engine; otherwise, false.

features

A string or array of strings specifying the feature(s) to be tested.

Examples

JScrewIt.areFeaturesAvailable("NO_IE_SRC")

JScrewIt.areFeaturesAvailable(["ATOB", "GMT", "NAME"])

Notes

If features is an empty array or undefined, the return value is true.

This function throws a ReferenceError if some unknown features are specified.

JScrewIt.areFeaturesCompatible(features)

Returns true if the specified features are compatible with each other.

features

A string or array of strings specifying the feature(s) to be tested.

Examples

JScrewIt.areFeaturesCompatible(["V8_SRC", "IE_SRC"]) // returns false

JScrewIt.areFeaturesCompatible(["DEFAULT", "FILL"]) // returns true

Notes

If features is an empty array or undefined, or if it only specifies one feature, the return value is true.

This function throws a ReferenceError if some unknown features are specified.

JScrewIt.encode(input, wrapWithEval, features)

Encodes a given string into JSFuck. Returns the encoded string.

input

The string to encode.

wrapWithEval

If this parameter is truthy, the return value evaluates to a function that runs the specified string as JavaScript code. If this parameter is falsy, the return value evaluates to a string equivalent to the specified input.

features

A string or array of strings specifying the feature(s) available on the engine that evaluates the encoded output. If this parameter is an empty array or undefined, DEFAULT is assumed: this ensures maximum compatibility but also generates the largest code. To generate shorter code, specify some features.

Notes

This function throws a ReferenceError if some unknown features are specified.

JScrewIt.FEATURE_INFOS

This is a container mapping feature names to descriptors. A feature descriptor is an object with a set of properties defining the feature.

Feature descriptor properties

name

Name of the feature.

description

A short description of the feature in plain English.

available

true if the specified feature is available on the current engine; otherwise, false.

includes

An array of feature names implied by this feature. If a feature is available, its includes are, too. If a feature is not available, other features including it are also not available.

excludes

An array of feature names not compatible with this feature. If a feature is available, its excludes are not.

Examples

This will return an array with the names of all features supported by JScrewIt:

Object.getOwnPropertyNames(JScrewIt.FEATURE_INFOS)

Links

• JSFuck
• Original discussion at Sla.ckers.org