Environment variables store configuration outside your code. Think of them as a settings file - change settings without changing code.
Like game settings (volume, difficulty) stored separately from the game code. Environment variables store API keys, database URLs, etc. outside your code - change environments without code changes!
Why Use Them?
- 🔒 Security: Keep secrets out of code
- 🔄 Flexibility: Different settings per environment
- 📦 Portability: Same code, different configs
- 👥 Team Collaboration: Each dev has own settings
Common Variables
- 🔑 API_KEY: Third-party service keys
- 💾 DATABASE_URL: Database connection
- 🌐 PORT: Server port number
- 🏷️ NODE_ENV: development/production
- 📧 EMAIL_SERVICE: Email provider settings
How to Use
// Access environment variable
const apiKey = process.env.API_KEY;
const dbUrl = process.env.DATABASE_URL;
.env File
API_KEY=your_secret_key_here
DATABASE_URL=postgres://localhost/mydb
PORT=3000
NODE_ENV=development
Best Practices
- 🚫 Never Commit: Add .env to .gitignore
- 📝 Document: Provide .env.example
- 🔐 Secrets: Use for sensitive data
- ✅ Validate: Check required variables exist
Environments
- 💻 Development: Local machine
- 🧪 Testing: Test database
- 🎭 Staging: Pre-production
- 🚀 Production: Live site
The bottom line: Environment variables store configuration outside code. Like a settings file, they let you change behavior without changing code!