Installation

npm install dotenv

How It Works

• Create a .env file in the root directory:

KEY=your-secret-key
API_URL=https://api.example.com

• Load environment variables in your Node.js app:

 // ES Module
import 'dotenv/config';
const key = process.env.KEY;

 // CommonJS
require('dotenv').config(); 
const key = process.env.KEY;

• Ensure .env is in .gitignore to prevent exposing sensitive data.

Advanced Usage

Custom Path

Specify a custom .env file location:

require('dotenv').config({ path: './config/.env' });

Expanding Variables

Use variables inside .env:

DB_USER=admin
DB_PASS=secret
DATABASE_URL=mysql://${DB_USER}:${DB_PASS}@localhost:3306/mydb

Load them in Node.js:

require('dotenv').config({ expand: true });
console.log(process.env.DATABASE_URL);
// Output: mysql://admin:secret@localhost:3306/mydb

Using in Scripts

Instead of manually requiring dotenv, you can load it automatically when running your script:

node -r dotenv/config server.js