Utilize Environment Variables in Your Node.js JavaScript Application: A Node.js Tutorial

To use environment variables in a Node.js JavaScript application, you can follow the steps below:

Step 1: Create a new Node.js application or open an existing one in your preferred text editor or IDE.

Step 2: Create a new file called .env in the root directory of your Node.js application. This file will contain your environment variables in the format KEY=VALUE.

Step 3: Add your environment variables to the .env file. For example, you can create a variable called PORT and set its value to 3000:

PORT=3000

Step 4: Install the dotenv package by running the following command in your terminal:

npm install dotenv

Step 5: Import the dotenv package at the top of your main Node.js file (e.g., index.js) and call the config() method to load the environment variables from the .env file:

require('dotenv').config();

Step 6: Access your environment variables in your Node.js application by using the process.env object. For example, you can access the PORT variable defined in the .env file as follows:

const port = process.env.PORT || 3000;

Step 7: Use the environment variables in your Node.js application as needed. For example, you can use the port variable to listen on a specific port for incoming connections:

app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});

Step 8: (Optional) You can also set default values for your environment variables by providing fallback values in case the variable is not defined in the .env file. For example, the PORT variable fallback to 3000 if it is not defined:

const port = process.env.PORT || 3000;

Step 9: (Optional) You can create multiple environment files (e.g., .env.dev, .env.prod, etc.) and specify which file to load based on the NODE_ENV environment variable. For example, you can create a .env.dev file with development environment variables:

require('dotenv').config({ path: `.env.${process.env.NODE_ENV || 'dev'}` });

Step 10: (Optional) You can skip the installation of the dotenv package and use custom logic to load environment variables from the .env file. For example, you can read and parse the .env file using the fs module and set the environment variables manually:

const fs = require('fs');
const dotenv = require('dotenv');

const envConfig = dotenv.parse(fs.readFileSync('.env'));
for (const key in envConfig) {
  process.env[key] = envConfig[key];
}

That’s it! You have successfully learned how to use environment variables in a Node.js JavaScript application. By following these steps, you can securely manage sensitive information such as API keys, database credentials, and other configuration settings in your Node.js applications.