Protecting JavaScript Code


Since its introduction in 1995, JavaScript has been an essential interpreted language in the web development world. The language has rich scripts that can be used in web applications and help in the interactivity of web technologies both on the client and server-side. On the client-side JavaScript code has functionalities to work with text, regular expressions, and the DOM amongst much other functionality. JavaScript code is embedded in the front–end page thus making it visible to anyone who visits the website /application and chooses to ‘View Source’ of the page. Because scripts are also open to various vulnerabilities and can be used to steal users’ sensitive data or be used to reverse engineer the application or source, developers try to protect/conceal their JavaScript code from users. This article discusses how developers can protect their JavaScript code from user manipulation or malicious use.

The Nature of JavaScript code

JavaScript functions may be implemented internally to work text or simply internal functions but largely complex. JavaScript code relies on external APIs to work on dates, regular expressions, etc. and these scripts are normally open to the public and this compromises the use of JavaScript code in all websites/applications. Most developers have argued that it is very difficult or almost impossible to hide or protect your JavaScript from users’ access or reverse engineering of application source code through scripts.

Protect your JavaScript code

The most common technique of hiding JavaScript code is code ‘Obfuscation’. This method renders software unintelligible but maintains the normal functionality of the application. It deals with the renaming of variables, changing and rearranging code, encrypting the original algorithm, data structures, or code logic, with the sole objective of making it virtually impossible to understand to users with malicious intentions.
Several methods have been tried to hide and protect JavaScript code, including:
  • JavaScript Obfuscator
  • UglifyJS
  • Jscrambler
All JavaScript protection methods try to hide the code from the knowledgeable user who might try to decipher the hidden logic and still manage to manipulate the code.

JavaScript Obfuscator

Lately, this method has been known to be the most effective way of protecting your JavaScript code. This tool includes complex ways of intelligently transforming the ordinary code into a series of unreadable characters and breaks the application logic once anyone tries to decipher the code. It also compresses the code so that it becomes scalable.
In its protection features, JavaScript Obfuscator includes:
Name Obfuscation
Replaces identifiers with a complex sequence of characters. This means that it checks across the entire application where the identifier is being used and replaces it accordingly.
String Encryption
All strings in the code are encrypted so that they cannot be read or decrypted and attackers have no way of figuring out the strings and figure out the strategic logic of the application.
Control Flow Obfuscation
It alters the flow of control in the application but gives the same results as the original control flow.
Dead-Code Insertion
Applies useless code that is not run when the real application runs. This is simply meant to confuse the intended attacker.
Minification and Compression
It minifies JavaScript files, making the JavaScript applications load faster and reduces bandwidth consumption.


Several attempts have been made to try and hide or protect JavaScript code but they have never been proven to be 100% accurate since one way or the other attackers can always find a way to decipher the code and reverse engineer the code or use it maliciously. It is good practice in modern-day development to try and protect code using whichever tool of your choice, as long as it does not leave the code open for attackers' scramble.