React Environment Variables: .env Return Undefined

As a React developer, you may have encountered a situation where your environment variables defined in the .env file are returning undefined in your React application. This can be frustrating, but fear not! In this article, we will explore a couple of solutions to fix this issue.

Solution 1: Restart the Development Server

One common reason for environment variables returning undefined is that the development server needs to be restarted after making changes to the .env file. This is because the server loads the environment variables only during the startup process. So, if you make any changes to the .env file, you need to restart the server to reflect those changes.

To restart the development server, simply stop the server by pressing Ctrl+C in the terminal where it is running, and then start it again using the npm start command.

Solution 2: Check Variable Name and Usage

Another reason for environment variables returning undefined could be a mismatch between the variable name in the .env file and its usage in your code. Make sure that the variable name is spelled correctly and that you are accessing it correctly in your React components or other files.

Let’s say you have an environment variable named REACT_APP_API_KEY defined in your .env file. To access this variable in your code, you need to prefix it with process.env like this: process.env.REACT_APP_API_KEY.

Here’s an example of how you can use an environment variable in a React component:

{`
import React from 'react';

const MyComponent = () => {
  const apiKey = process.env.REACT_APP_API_KEY;

  return (
    

      
My Component
      API Key: {apiKey}
    
  );
};

export default MyComponent;
`}

Make sure that you have also added the prefix REACT_APP_ to your variable names in the .env file. React requires this prefix for security reasons.

Conclusion

When your React environment variables defined in the .env file return undefined, it can be due to either not restarting the development server after making changes to the .env file or a mismatch between the variable name and its usage in your code. By following the solutions mentioned above, you should be able to resolve this issue and access your environment variables successfully.

Remember to restart the development server whenever you make changes to the .env file, and double-check the variable names and their usage in your code. Happy coding!