Protecting Your React.js Source Code with Jscrambler
Tags: jscrambler, react, javascript, security
Published: 2019-02-04 15:31:24

---
title: Protecting Your React.js Source Code with Jscrambler
published: true
description: In this step-by-step guide, you'll learn how to protect your React.js application with Jscrambler to prevent code theft and reverse-engineering.
tags: Jscrambler, React, JavaScript, Security
canonical_url: https://blog.jscrambler.com/protecting-your-react-js-source-code-with-jscrambler/?utm_source=dev.to&utm_medium=referral
cover_image: https://thepracticaldev.s3.amazonaws.com/i/j0am404500y16m33zc1f.jpg
---

[React.js](https://reactjs.org/) is one of the most popular JavaScript libraries. The 2018 "State of JavaScript" survey puts React as the [front-end framework of choice](https://2018.stateofjs.com/front-end-frameworks/overview/), with 65% of responders stating that they have used it and would use again.

With its elegant programming style, rich package ecosystem and good documentation, React has found its way into powering the applications of large enterprises. Specifically, the developer survey found that **18% of responders which are using React work for companies with over 1000 employees**.

As we know, the very nature of JavaScript means it can't be encrypted and can easily be accessed on the client-side or even tampered with.

> Because React powers enterprise-grade applications, it requires an enterprise-grade security solution such as Jscrambler.

This tutorial will explain how to integrate Jscrambler seamlessly into React's build process in just a few minutes. You'll learn how to protect your React source code with the most advanced polymorphic obfuscation techniques, along with code locks and self-defensive capabilities.

## Pre-Requisites

Only two things are needed to properly integrate Jscrambler into the React build process: **creating a React app** and **configuring Jscrambler**. We will highlight both below.

### How to Create a *React* Application

For the purposes of this tutorial, we will be using a `create-react-app` boilerplate app. To get started, we will need to install it using npm:

```bash
npm i -g create-react-app
```

This will download `create-react-app` and install it globally with all the required dependencies for the latest React version.

Now, we're ready to create our boilerplate app, which we'll use as the basis for this tutorial. Start by creating this new app with the following command:

```bash
create-react-app react-jscrambler-boilerplate
```

After the installation finishes, we can run our newly created boilerplate app:

```bash
cd react-jscrambler-boilerplate
npm start
```

Our new React app will run on development mode and appear at `localhost:3000`. Check if everything is in place before moving to the next step. For further help on getting started with `create-react-app`, see the [official documentation](https://reactjs.org/docs/create-a-new-react-app.html).

![Default React App Home](https://thepracticaldev.s3.amazonaws.com/i/kmyspzukjlq677y03neu.jpg)

The base project structure of our *React* application is as follows:

```
react-jscrambler-boilerplate/
|-- package-lock.json
|-- package.json
|-- yarn.lock
|-- build/
| |-- static/
| | |-- css/
| | |-- js/
| | |-- media/
|-- node_modules/
|-- public/
|-- src/
```

* `package.json` contains all the configurations which are related to npm such as dependencies, version and scripts.

* The `src` directory features all the source code of the application. The sources are then built and packed into the `build` directory. This is where our protected HTML and JavaScript files will be placed after the build.

### How to Configure Jscrambler

All of Jscrambler's configuration will reside inside a single file: `.jscramblerrc`. As such, we will need to create this file to specify which transformations we wish to use.

The quickest way to achieve this is via the [Jscrambler Web App](https://app.jscrambler.com/dashboard?utm_source=dev.to&utm_medium=referral). Once there, create a new app. Now, in the *Application Modes* tab, select the Language Specifications and application type. Next, select the transformations you want (check the *Templates* and *Fine-Tuning* tabs). In this tutorial, we'll be selecting the *Obfuscation* template. If you need help with these steps, please refer to our [guide](https://blog.jscrambler.com/jscrambler-101-how-to-use-the-cli/?utm_source=dev.to&utm_medium=referral).

Now, we simply have to download a **JSON file with all this configuration**, which will be used only for quickly getting the required settings.

<center>![Download Jscrambler JSON](https://blog.jscrambler.com/content/images/2018/08/jscrambler-101-first-use-download-json.png)</center>

Now, let's create a new file named `.jscramblerrc` on the React project’s root folder. Open the `jscrambler.json` file we just downloaded and copy all its contents to the `.jscramblerrc` file. After that, we just have to add two new sections to `.jscramblerrc`, which are `filesSrc` and `filesDest` (see below). Your final `.jscramblerrc` file should look like this: 

```json
{
 "keys": {
   "accessKey": <ACCESS_KEY_HERE>,
   "secretKey": <SECRET_KEY_HERE>
 },
 "applicationId": <APP_ID_HERE>,
 "filesSrc": [
   "./build/**/*.html",
   "./build/**/*.js"
 ],
 "filesDest": "./",
 "params": [
   {
     "name": "whitespaceRemoval"
   },
   {
     "name": "identifiersRenaming",
     "options": {
       "mode": "SAFEST"
     }
   },
   {
     "name": "dotToBracketNotation"
   },
   {
     "name": "deadCodeInjection"
   },
   {
     "name": "stringConcealing"
   },
   {
     "name": "functionReordering"
   },
   {
     "options": {
       "freq": 1,
       "features": [
         "opaqueFunctions"
       ]
     },
     "name": "functionOutlining"
   },
   {
     "name": "propertyKeysObfuscation"
   },
   {
     "name": "regexObfuscation"
   },
   {
     "name": "booleanToAnything"
   }
 ],
 "areSubscribersOrdered": false,
 "applicationTypes": {
   "webBrowserApp": true,
   "desktopApp": false,
   "serverApp": false,
   "hybridMobileApp": false,
   "javascriptNativeApp": false,
   "html5GameApp": false
 },
 "languageSpecifications": {
   "es5": true,
   "es6": false,
   "es7": false
 },
 "useRecommendedOrder": true,
 "jscramblerVersion": "5.<X>"
}
```

Because we got this information directly via the Jscrambler Web App, our `accessKey`, `secretKey` and `applicationId` fields are already filled. If you wish to retrieve them manually, refer to our [guide](https://blog.jscrambler.com/jscrambler-101-first-use/?utm_source=dev.to&utm_medium=referral).

It's important to note that the `params` section specifies the transformations that will be used to protect your React app. **These can be hand-picked by you**, by selecting them in the Web App or setting them manually. You can find documentation on all the available transformations [here](https://docs.jscrambler.com/code-integrity/documentation/transformations?utm_source=dev.to&utm_medium=referral).

You can also change `filesSrc` to match the files you need/want to protect. For our example — and all React apps — we recommend protecting the `.html` and `.js` files. Certainly, with a better understanding of the project, you may identify what’s critical and essential protecting.

By using `filesDest: './'`, the files we send to protect will be overwritten by their protected version.

## Integrating Jscrambler in the Build Process

Using the CLI is likely the most common way of generating your build. We will use our boilerplate app to showcase how to integrate Jscrambler into the build process.

The first step of our integration with *Jscrambler* is installing the [Jscrambler API Client](https://github.com/jscrambler/jscrambler/tree/master/packages/jscrambler-cli). Simply run:

```bash
npm i jscrambler --save-dev
```

To integrate Jscrambler in our application's build process via the CLI, we need to create a CLI hook in the *scripts* section of `package.json`. The section should look like this:

```json
"scripts": {
  "start": "react-scripts start",
  "build": "react-scripts build && jscrambler",
  "test": "react-scripts test",
  "eject": "react-scripts eject"
},
```

The specific `"build": "react-scripts build && jscrambler"` hook will trigger the `jscrambler` command after the build process is finished.

In order for this command to be executable, **we need to make sure that the `.jscramblerrc` file that we created before is in our project's root folder**.

We are now ready to protect our code and build our application via the CLI:

```bash
npm run build
```

This will create the protected production files on `build/static/`.

And you're done! Now all your HTML and JavaScript files are protected with Jscrambler against code theft and reverse-engineering. Remember that you can always fine-tune your protections to manage eventual performance hits. If that's the case, be sure to follow our [tutorial](https://blog.jscrambler.com/jscrambler-101-code-annotations/?utm_source=dev.to&utm_medium=referral).

**Note:** If you have ejected your project, you can also protect the files using the Jscrambler [webpack plugin](https://github.com/jscrambler/jscrambler/tree/master/packages/jscrambler-webpack-plugin).

## Testing the Protected React App

As a final step, let's check if the app is running successfully with the newly-protected source code. Start by installing the required dependencies:

```bash
npm i -g serve
```

Next, let's simply deploy the app build files to a local development server:

```bash
serve -s build
```

Now, as you should be able to see on the terminal, you can run this server on two ports. One which is publicly available, and another which is specific to your machine.

Open the provided URL and your app will start in the browser.

You can now check what your protected files look like. This can be achieved simply by opening the browser's debugger and opening the files from the "Sources" tab. The protected code should look like this:

![Protected React Code - Chrome Debugger](https://thepracticaldev.s3.amazonaws.com/i/3gibi73lub7dhjkzq8lo.jpg)


## Conclusion

There are no doubts that *React* is a crowd favorite, from individual developers to large enterprises.

If you're building React applications which have sensitive logic, want to prevent **reverse-engineering, licensing violations, and tampering**, a security solution such as Jscrambler is a must.

Integrating Jscrambler into React's build process is simple and enables protecting your code with the most sophisticated **polymorphic obfuscation**, **code locks**, and **self-defensive** capabilities.

This all comes with premium support, so be sure to [contact the Jscrambler support team](mailto:support@jscrambler.com) if you have any questions!