Mastering ReactJS Environment Variables: A Complete Guide

Imagine this: You’ve just launched your new ReactJS application. It’s sleek, fast, and users are loving it. But behind the scenes, there’s a problem brewing. Sensitive data—like your API keys and database credentials—are unknowingly exposed in your code, putting your application at risk. It’s an easy mistake to make, but one that could cost you both time and trust. The good news? There’s a simple solution: mastering ReactJS environment variables.

In this guide, we’ll walk you through the essential steps to secure your data, optimize performance, and ensure that your app is scalable and future-proof. Ready to safeguard your application?

Introduction to Environment Variables

In programming, an environment is the condition in which the code you create runs. Each environment corresponds to a specific software development phase. It can be application building, testing, or deployment. 

Variable is a basic element of any programming language. They show the memory locations with the data the program employs in its operations.  An environment variable has a value that is configured external to the program. They have values that impact the functioning of the program. 

What Are Environment Variables?

Environment variables have the configuration data of an app. They are available to an app dynamically when it runs. You can get their actual value from any outside source or users. System or operating system-defined EVs are specified by your system. Alternatively, in user-defined EVs, the values are specified by the user via configuration files. Here are their most important points:

• Variable values can be configured in users’ profile settings or inside the terminal through specific commands.
• The value of an EV can be modified and saved at any time. 
• Any application working in the same environment has the EV accessible. The app can utilize its value.

Importance of Environment Variables in Web Development

Environment variables are key-value pairs that are configured on a local setup. You can also configure them in the hosting service and not in plain code. However, they can be used easily in code, which strengthens the code’s security. 

EVs also ensure adaptive code. For instance, if the React code uses an EV with the name contact_number, it must show it on the website in the necessary places.

What if you want to change it later? You will need to do it in an environment variable configuration. If it had been plain code, you would have needed to change it everywhere. It is very time-consuming, but EVs help you in this place.

Here are other major ways that show their importance in web development:

• EVs enable setting up the configurations for different environments and their proper management.
• EVs effectively keep confidential data. Database passwords and API keys are the most common examples.
• Since EVs separate the app’s configuration data from the code, you do not need to update the code.
• Apps are seamless to maintain with EVs.
• Correctly formatted EVs eliminate the chances of unintended errors.
• You can run your program on different services without getting the code changed. 

As a leading ReactJS Development Company, eSparkBiz has helped brands of varying sizes to use environment variables to achieve greater efficiency. For instance, we have helped tech startups with API configuration management through which they could change between local and production build APIs without modifying the actual code. This, in turn, made their deployment period short and simplified. 

ReactJS and Environment Variables

🔐 Using environment variables in #ReactJS keeps your sensitive data secure and makes switching between dev, test, and prod a breeze.

Remember: always prefix with REACT_APP_ for Create React App!📷 #WebDevelopment #Security #javascript pic.twitter.com/kywEP5hRGl

— eSparkBiz (@eSparkBiz) October 10, 2024

React’s environment variable is crucial to manage sensitive data and boost your application’s security. Like usual EVs mentioned above, they eliminate the tedious practice of accessing data from the back-end using long alphanumeric API credentials.

These variables in React are found through a global process.env Object. This object is given your environment via NodeJS. When using Node with ReactJS, it is essential for EVs to have the prefix REACT_APP_, which facilitates their identification as customized EVs. Understanding the variable is critical in using them correctly in ReactJS.

Overview of Environment Variables in React

Environment variables are essential elements of development in ReactJS. They allow you to store globally scoped values in the environment where you code. As a result, the variable is there throughout your codebase.

Through ReactJS EVs, you can specify configurations particular to the environment where your code is executed. So, for example, you can use different API URLs for varied environments like development, staging, and launch. Also, with EVs in ReactJS, you can deploy your app in any environment without modifying the code.

Example: eSparkBiz’s experts integrated React environment variables into the CI/CD pipeline of a SaaS company. This enabled the company to set configuration values automatically during the build process according to the specific environment. Through this efficient automation, the chances of making manual errors were reduced, and every build was set up correctly for its deployment environment.

Default Environment Variables in Create React App

In Create React App project, the EVs must have the prefix REACT_APP_. If the variable does not have this prefix, it will not be accessible to you in the program’s code. For example, if you wish to specify an API key, you will use the following: 

REACT_APP_API_KEY=your_api_key_here

Us of Variable without this prefix will not be taken during the process. This is because it can lead to an inadvertent exposure of sensitive data.

Setting up Environment Variables in React

To set up ReactJS env variable, you can create one or more than one .env files. After that, you access the EVs in the file.

Creating .env File in React

To create and define EVs in a React app, you keep them in a plain text file. This file has a .env extension present in the project’s root directory.  Those who use the Create React App should know that it uses the dotenv library to read EVs in a .env file. After that, they are loaded into a `process.env` object. 

As the application scales, create several .env files for different environments. becomes imperative. The main file usually has the shared environment variables. Files with different suffixes have variable for other environments, such as development and staging. 

At runtime, the dotenv library loads the right environment variables from the matching .env files. It substitutes the reference to every EV name within the codebase with its existing value.

You can now begin adding all the environment variables to your .env files. As mentioned earlier, in a React app created with Create React App, EVs have the prefix REACT_APP_. Now, the environment variable name will be on the left side of the equals sign, while the real value will be on the right. 

Naming Conventions for React Environment Variables

Adhering to particular naming conventions for ReactJS environment variables is necessary for the correct functionality. Here are the naming conventions to follow:

• Every variable should begin with the REACT_APP_ prefix. An example can be REACT_APP_API_URL= https://api.example.com
• The allowed characters in the naming convention are uppercase letters, digits and underscores. 
• Your variable’s name must not start with a digit but a letter.
• Do not use spaces or enclose values when specifying values for EVs.

Accessing Environment Variables in a React Application

In order to access EVs in a React code, use process.env. It is a global object provided by Node.js at runtime. So, if you do not have Node.js in your browser, using Webpack becomes crucial. 

Suppose you have an EV named REACT_APP_API_KEY. To access it, first find the API key in your React EV. Then, use the Javascript command:

const apiKey = process.env.REACT_APP_API_KEY;

Use Environment Variables for Different Environments

When you use the Create React App to create your application,  it installs several packages. Through them, you can configure different environments for different phases of development in the app.

By default, the .env package is installed. .env files can also be used to define ReactJS environment variables for various environments. Let us explore them in detail.

Development, Testing, and Production Environment Variables

Following are the EVs you should use to configure environments at varying software development periods: 

• env.local: Local overrides: Use it to define environment variables for development, testing and production environments.
• env.development: Use it to set up a product EV in ReactJS.
• env.test: This should be used to set up a test environment variable.
• env.staging: This is to set up a staging environment variable

Managing Multiple Environments in React

The various environments in React can be difficult to manage if you do not follow a specific approach. To work with multiple environments seamlessly, follow these steps:

• Use the command npm start with i -D env-cmd to install the Node.JS utility env-cmd.
• At the root of your React project, add the .env file as follows: REACT_APP_API_ENDPOINT = https://default.example.com
• Now, add the .env.qa file using the command REACT_APP_API_ENDPOINT = https://qa.example.com
• The next step is adding the .env.staging file. For it, use this command: REACT_APP_API_ENDPOINT = https://stage.example.com
• Lastly, add the .env.production file. Use the command REACT_APP_API_ENDPOINT = https://production.example.com

Do not forget to update your package.json script. You can now use the following syntax in the program’s code:

const baseUrl = process.env.REACT_APP_API_BASE_URL;

Example: eSparkBiz helped a top FinTech firm enhance the scalability of their React app through environment variables. We managed the app’s configurations through EVs, so when it grew and moved between different development environments, the same codebase was reused with different settings. This reduced errors and made the deployment of the application streamlined. 

Conditionally Accessing Environment Variables Based on the Environment

In order to conditionally access EVs according to the environment, you should follow these steps:

• Make different .env files for every specific environment. Examples include .env.development, .env.production, and the like. 
• Ensure that your EVs have the REACT_APP_ prefix.
• Now, use the process.env. NODE_ENV variable to conditionally access the EVs based on the active environment. This variable will also allow you to conditionally render react component.

This example illustrates conditionally accessing the EVs:-

const apiUrl = process.env.REACT_APP_API_URL;

console.log('Current environment:', process.env.NODE_ENV);

console.log('API URL:', apiUrl);

if (process.env.NODE_ENV === 'development') {

console.log('Running in development mode');

} else if (process.env.NODE_ENV === 'production') {

console.log('Running in production mode');

}

Securing Environment Variables in React

ReactJS EVs should be secured for you to store sensitive data. The crucial data can be easily misused if steps are not taken to secure EVs. Depending on your case, this can lead to operational or financial damage. 

To protect React environment variable, you should first know about the kinds of sensitive data in them and ways to avoid their exposure. 

Sensitive Data in Environment Variables

You can store a lot of private data in ReactJS env variable.

The Sensitive Data include:-

• API key that allow easy access to services like payment gateways.
• Database credentials like usernames and passwords should be private.
• Encryption keys protect data privacy.
• Certificates, such as private certificates and keys
• Service secrets or tokens grant you access to an internal service that is otherwise restricted.

Avoiding Exposure of Secrets in React Applications

Private or sensitive data must be hidden in React applications. By following the ReactJS best practices for the same, you’ll be able to prevent the secrets of your React apps from getting exposed. 

• Keep passwords and API keys out of your .env file. Instead, keep them as EVs in your server.
• Keeping API key safe in an environment variable manager is another option.
• Put your environment variable in a .env file. Keep this file excluded from source control (src folder).
• Encrypt the variable with the secure-env package.
• Encrypt the split-up keys and go a step further by employing code-splitting.
• If it is a third-party API, keep it in EVs.
• Perform an audit of the env variable regularly. This way, no sensitive information will be exposed.

Common Use Cases for ReactJS Environment Variables

Environment Variable have plenty of uses in a ReactJS application. They store private information and allow you to customize the app’s functionality in different environments. The applications of EVs for ReactJS are below.

API Keys and Endpoints

You can have various API endpoints for your every software lifecycle environment. EVs also store sensitive information like API URL, key and credentials. You can configure them for API’s varied keys and correct URL. The Rapid API key and the Weather API key are two good examples.

Configuring Application Behavior

EVs are also used to modify the React project’s behaviour. The behaviour of the application you are building can be changed as per the environment or context. For instance, the app can show different content when the app is in development mode. 

Toggling Features

EVs keep toggle values. It means that they can allow or disallow features of an app according to those values. This, in turn, allows you to gain observability over the functioning of your application without deploying it again. 

Example: Our SaaS client toggled features using React environment variables and confidently implemented new features into their product. Dynamic feature toggles allowed it to test new functionalities without changing the code, which, in turn, enhanced its feedback loops and overall development.

Debugging Issues with Environment Variables

When React environment variable do not work as intended, many issues occur. Your API key may disappear, or the configuration settings may become incorrect, resulting in unwanted application errors.

Some major reasons for issues with EVs include the following:-

• You have not used a lightweight package like dotenv to load the variable.
• You have not set the EV appropriately.
• Wrong file location
• The development server has not been started again after changing the variables. 
• Not running the right build command matching with the file of a specific environment.

Common Errors When Using Environment Variables

You can encounter various errors if you have used React environment variable incorrectly.

Some prevalent ones include the following:-

• Environment Variable not set – If the spelling of your EV is incorrect, you will see this error.
• Environment variable set to a directory that does not exist – This happens when the directory to which the EV points is not in existence.
• Environment variable not set properly – Using a file name with a spelling inconsistency again leads to this error.
• Environment variables not logging – The absence of the prefix REACT_APP_ leads to this error.
• Invalidor missing environment variable – It has several causes, such as not restarting the server after modifying the EV or putting the wrong prefix.

Troubleshooting Missing or Undefined Variables

Due to the missing or un-defined environment variable, the React application does not work as desired.

Use these troubleshooting approaches:-

• Ensure that proper naming conventions, such as putting the correct prefix, are followed.
• Restart the server after you add the variable. Otherwise, the changes will not show.
• The root folder should have the .env files. Remove it from the source folder if it is there.
• No spaces or quotes should be there in any .env file name. 
• Check for proper configuration of the EV in its corresponding environment.
• Remove all trailing commas after naming the .env files.

Best Practices for Debugging Environment Variables

You will not like your environment variable to encounter glitches.

So, follow these best practices for debugging them and make your application free of errors:-

• Always restart the server when updating the .env files in any way.
• To prevent inadvertent commits of files with classified data, use .gitignore files. They command version control system not to consider certain files.
• Follow a single naming convention for each EV as prescribed above.
• Set EVs manually in the deployment settings in hosting platforms like Netlify and Heroku as they do not load  .env files automatically. 
• Confirm that all variables are loading right by using  console.log (process.env) in your application.
• Users of Webpack should configure the DefinePlugin. It will enable EVs to pass precisely in the build. 

Best Practices for Managing ReactJS Environment Variables

When you properly manage ReactJS environment variables, your application maintains its flexibility. So, you should know about the key security considerations and how to organize EVs for complex projects. 

Security Considerations to use Environment Variables

You already know that EVs have sensitive data. So, by following some security best practices, you can manage them well.

Here are the important security considerations:-

• Never store sensitive information, like API key, directly in your EV. Since EVs in React are embedded into the build, they can be accessed through the React Developer Tools. 
• .env files with confidential data should be added to .gitignore files. Never push them to public repositories. 
• Besides adding .env files to .gitignore files, create a new file in your repository’s root. Put the name of the .env file in a new following line.
• Use a cipher to make the key by first generating an encryption key. It can be securely kept as an EV.
• Minimize exposing your variable. Only use those that are important for the front end. Otherwise, a malicious user can compromise its security.
• Make your code easy to use by having a single name for an EV, even for different environments. 

Keeping Environment Files Out of Version Control

It is extremely important to keep your EVs out of version controls like Git. React EVs hold highly confidential information. Committing them to a Version Control exposes the sensitive information to the person who can access the repository.

The importance of keeping away EVs out of Version Control is more for those owning open-source projects. Hard-coding the key into your React project’s code leads to mobility security risks. Those who know your source code can access it. 

Also, Version Control System like Git have a list of all commits. Thus, even if you remove your .env file from the repository there, someone can still get it from the commit history. So, it is essential to never commit to keeping EVs in the Version Control.

Organizing Environment Variable for Large Projects

If you are managing a big and complex project, it becomes more priority to organize EVs properly. An effective organization will help you avoid chaos as the project becomes intricate with numerous EVs.

Use these techniques to organize the variable:-

• Use a .env file to read and change your EVs when needed quickly. 
• Create or edit a current .gitignore file and keep your .env to it.
• Add .env to your .gitignore file and commit this modification before you add your .env to prevent committing an early version of your .env to Version Control.
• Use descriptive naming conventions for the different variables for better readability. 
• Configure your CI/CD pipelines to take care of all variables according to the deployment stage.
• Clearly document all env variables you are using. You should define their purpose and expected values.

Third-Party Tools for Managing Environment Variables

Sometimes, using custom environment variables to store configuration data and credentials can pose significant security hazards. Highly sophisticated cybercriminals can access a virtual machine and access the variable. Not only this, but the logging and monitoring tools used by developers can also inadvertently log EVs, which becomes accessible to third party service. Using external secrets management tools will help you overcome management issues. 

Using dotenv with React

Dotenv makes the process of loading environment variables in React apps easier. As a result, you can configure apps across various environments without any issues. 

The dotenv file contains environment-specific variables, which you need to keep outside your codebase. This, in turn, boosts manageability and separation of concerns. Dotenv allows you to manage configurations that vary between the different environment in an organized manner.

In a React application, using Dotenv lets you keep your sensitive information, such as API keys and database connections, out of your main code base. So, you can update this information without altering the code. 

External Secrets Management Tools (Vault, AWS Secrets Manager)

External secrets management solutions offer a centralized way to protect and manage secrets. Those like AWS Secrets Manager and HashiCorp Vault provide secure secret storage.

AWS Secrets Manager takes care of storing, rotation, and retrieval of secrets. These include database credentials and key. It encrypts secrets via AWS Key Management Service, and the user specifies the access permissions using AWS Identity and Access Management.

HashiCorp Vault can manage numerous backends and offers secure secret storage. It also has stringent controls to access secrets in on-premises or multi-cloud environments.

External secrets management tools provide granular access control and enhance the security framework for managing secrets. 

Performance Considerations with Environment Variables

Environment variables are vital to your application’s configuration. They also influence how secure and resilient your application is. Moreover, system EVs are crucial for properly executing various shell scripts and system commands. So, optimizing EVs is crucial for a high-performing application. 

Impact of Environment Variables on Build Size

The impact of EVs on build size results from their size limitations. For instance, the cloud platform Vercel permits 64KB for all your environment variables combined in each deployment. Specific variable have a 64KB limit, while the Edge Functions have a 5KB limit. 

The size impacts the overall data that can be transferred during builds. If limits are reached, the performance is impacted.

The CI/CD platform Bitrise has a 120KB limit for the size of EVs, while the individual limits are 20 KB. Going beyond the limits causes failed builds, or you will need to refactor.

Optimizing Performance when Using Environment Variables

Environment variables make your application adaptable for different hosting platforms, database providers, and development server configurations, and you do not have to change any code. This flexibility makes the scalability of your application easier.

Some ways to optimize performance when using EVs are mentioned below:-

• Keep all the configuration settings and information in a specific .env file.
• Use dotenv to load your EVs from a .env file during the coding process. 
• Confirm the EVs and parse them to avoid facing runtime errors.
• Include just the essential environment variables. It eliminates unnecessary latency during application initialization and prevents performance slowdown.
• Provide fallback values for the most significant Vite environment variables so that unwanted application failures can be avoided. 

Also Read: React Performance Optimization Tips to Adhere for Enhanced UI Results

Real-World Examples of Using Environment Variables in React Projects

By now, you are aware of the many benefits of using ReactJS environment variables. Their significance will become clearer when you look at real-world examples of their usage.

Handling API Keys in a React Application

eSparkBiz built API keys for a client who wanted a React application. To handle the keys well and keep them secure, we used environment variables. The dotenv module was used to load them. We added the API key to it and then examined the EVs in our React application. Moreover, we took advantage of a back-end proxy server and set it up between our client’s React project and the server application. In turn, it prevented the API key from showing in the front-end code. 

Managing Feature Flags with Environment Variables

Another real-world example of using EVs is when we managed feature flags with them successfully. We revamped features in a React application by designating feature flags in EVs. We used the EVs to render different features conditionally and used a build tool to manage them. Thus, we upgraded the React app with new features. 

Configuring Application Settings for Different Environments

We have also used EVs to configure varied application settings for different environments during software development. We created environment-specific configuration files to load the setup corresponding to a specific EV.

Hire ReactJS developers with expertise in using distinct environment specific settings for streamlining the whole process including particular deployment environments, such as development, production, and testing. Using environment variables, we kept the configuration distinct from the code, thus making software maintenance easy.

Chintan Gor

CTO, eSparkBiz

Enthusiastic for web app development, Chintan Gor has zeal in experimenting with his knowledge of Node, Angular & React in various aspects of development. He keeps on updating his technical know-how thus pinning his name among the topmost CTO's in India. His contribution is penned down by him through various technical blogs on trending tech. He is associated with eSparkBiz from the past 14+ years where one can get premium services.