Troubleshooting 'NODE_ENV is not recognized' Error in Windows Node.js

This error message occurs when you try to set the NODE_ENV environment variable within a Node.js script using the syntax SET NODE_ENV=production & node app.js. However, the SET command is specific to Windows batch files, and Node.js scripts themselves don't interpret it directly.

NODE_ENV and Node.js:

• NODE_ENV is a common environment variable used in Node.js applications to indicate the environment (e.g., development, test, production) the code is running in.
• Based on the value of NODE_ENV, your code might behave differently, such as enabling logging in development but disabling it in production for performance reasons.

Resolving the Issue:

Here are two effective ways to set the NODE_ENV environment variable in Node.js on Windows:

Using a Batch File:

• Create a .bat file (e.g., set-env.bat) with the following content:

SET NODE_ENV=production
node app.js

• Run this batch file to set the environment variable and then execute your Node.js application.

Using cross-env (Recommended):

• Install the cross-env package as a development dependency:

  npm install --save-dev cross-env
  

• In your package.json scripts section, replace SET NODE_ENV=production & node app.js with:

  "scripts": {
    "start": "cross-env NODE_ENV=production node app.js"
  }
  

Key Points:

• cross-env is a more versatile solution because it works consistently across different operating systems (Windows, macOS, Linux) without relying on platform-specific syntax.
• Choose the method that best suits your project setup and preferences.

Additional Considerations:

• Environment Variables in General: You can set environment variables permanently in your system settings or temporarily within your command prompt/terminal for a specific session.
• Project-Specific Environment Variables: Consider using tools like .env files or dedicated environment management solutions for more complex projects to manage environment variables effectively.

Example Codes for Setting NODE_ENV on Windows in Node.js

Using a Batch File (set-env.bat):

SET NODE_ENV=production
node app.js

Explanation:

• SET NODE_ENV=production: This line sets the environment variable NODE_ENV to the value production.
• node app.js: This line starts your Node.js application named app.js with the environment variable set.

How to Use:

1. Create a new text file in your project directory and name it set-env.bat.
2. Paste the code snippet above into the text file.
3. Save the file.
4. Double-click the set-env.bat file to run it. This will set the NODE_ENV variable and then execute your app.js script.

a. Install cross-env:

1. Open your terminal or command prompt and navigate to your project directory.
2. Run the following command to install cross-env as a development dependency:

npm install --save-dev cross-env

b. Update package.json:

1. Open your project's package.json file.
2. Locate the scripts section. This section defines scripts that can be run using npm commands.
3. If you have a script named start defined for running your application, replace the command within the start script with the following:

"scripts": {
  "start": "cross-env NODE_ENV=production node app.js"
}

• cross-env: This ensures consistent environment variable setting across different operating systems.
• node app.js: This starts your Node.js application.

1. With cross-env installed and the package.json script updated, simply run the following command in your terminal:

npm start

This will use cross-env to set the NODE_ENV variable to production and then execute your app.js script.

Choosing the Right Method:

• If you only need to set the environment variable for a single command, using a batch file is a quick solution.
• For more flexibility and cross-platform compatibility, using cross-env is the recommended approach.

• This approach sets the NODE_ENV variable globally for your entire system.
• Caution: Be mindful of potential conflicts with other applications that might rely on specific NODE_ENV values.

Steps:

1. Open the System Properties window. You can search for it in the Start menu.
2. Go to the Advanced system settings tab.
3. Click on the Environment Variables button.
4. Under System variables, look for a variable named NODE_ENV.
   • If it exists, double-click it and modify the value to production (or your desired environment).
   • If it doesn't exist, click New and create a new system variable with the name NODE_ENV and the value production.
5. Click OK on all open windows to save the changes.

Using a .env File (Requires Additional Package):

• This approach leverages a dedicated .env file to store environment variables specific to your project.
• You'll need a package like dotenv to load variables from the .env file into your Node.js application.

2. Add a line to the .env file like this:

   NODE_ENV=production
   

3. Install the dotenv package:

   npm install dotenv --save-dev
   

4. Require dotenv in your main application file (e.g., app.js) and call its config() method before accessing process.env:

   require('dotenv').config();
   
   console.log(process.env.NODE_ENV);  // Output: production
   

Using a Process Manager (For Production Environments):

• If you're deploying your application to a production server, tools like PM2 (Process Manager 2) can be used to manage the application process and environment variables.
• PM2 allows you to define environment variables specifically for your Node.js application within its configuration file.

• If you need a global setting for all your Node.js projects (use with caution), consider system environment variables.
• For project-specific environment variable management, using a .env file with dotenv is a popular approach.
• For production environments with process management tools, PM2 provides a robust solution for defining environment variables.