Node.js — Environment Variables

Accessing Environment Variables

console.log(process.env.NODE_ENV);
console.log(process.env.PORT);
console.log(process.env.DATABASE_URL);

Setting Environment Variables

# In terminal
export NODE_ENV=production
export PORT=3000

# Inline
PORT=3000 node app.js

# Windows
set NODE_ENV=production

dotenv Package

npm install dotenv

// Load at top of app
require('dotenv').config();

// Use variables
const port = process.env.PORT || 3000;
const dbUrl = process.env.DATABASE_URL;

.env File

NODE_ENV=development
PORT=3000
DATABASE_URL=postgres://localhost/mydb
API_KEY=your-secret-key

.env.example

NODE_ENV=
PORT=
DATABASE_URL=
API_KEY=

Best Practices

Practice	Description
Never commit .env	Add to .gitignore
Use .env.example	Document required vars
Validate on startup	Check required vars exist
Provide defaults	Fallback values

Mini Practice

1. Set environment variables
2. Use dotenv package
3. Create .env file
4. Validate environment on startup

Up Next

Continue with Error Handling — handling errors gracefully.