JavaScript Obfuscation/Deobfuscation

Obfuscation

Obfuscation is a technique used to make a script more difficult to read by humans but allows it to function the same from a technical point of view, though performance may be slower. This is usually achieved automatically by using an obfuscation tool, which takes code as an input, and attempts to re-write the code in a way that is much more difficult to read, depending on its design.

Run and test Javascript on online console

jsconsolejsconsole.com

Minificating a JavaScript

Code Minification involves compressing the code into a single, often lengthy line. This greatly reduces its readability by humans while maintaining its functionality from a technical perspective.

Online Resources for JavaScript Minifiers:

JavaScript Minifier & Compressor | Toptal®toptal

Packing a JavaScript

A packer obfuscation tool usually attempts to convert all words and symbols of the code into a list or a dictionary and then refer to them using the (p,a,c,k,e,d) function to re-build the original code during execution. The (p,a,c,k,e,d) can be different from one packer to another. However, it usually contains a certain order in which the words and symbols of the original code were packed to know how to order them during execution.

While a packer does a great job reducing the code's readability, we can still see its main strings written in cleartext, which may reveal some of its functionality. This is why we may want to look for better ways to obfuscate our code.

Online Javascript Obfuscator makes javascript code harder to read or understand.

Online Javascript Obfuscator - BeautifyTools.combeautifytools.com

Advanced obfuscation

Completely obfuscate the code and hide any remnants of its original functionality.

JavaScript obfuscator toolObfuscator.io

JSFuck - Write any JavaScript with 6 Characters: []()!+jsfuck.com

jjencode - Encode any JavaScript program using only symbolsutf-8.jp

aaencode - Encode any JavaScript program to Japanese style emoticons (^_^)utf-8.jp

Deobfuscation

Just as there are tools to obfuscate code automatically, there are tools to beautify and deobfuscate the code automatically.

Deobfuscation online tools

UnPackermatthewfl.com

JS NICE: Statistical renaming, Type inference and Deobfuscationwww.jsnice.org

Beautify minified JavaScript codes

Browser tool, CTRL+ALT+I and then click on the '{}' button on the Debugger tab which will Pretty Print the script into its propoer JavaScript formatting
Online resources like Prettier or Beautifiier