# Environment Variables — Express.js

Source: https://www.geekswithgeeks.com/en/expressjs/ex-config

> Keep secrets and per-environment settings out of the codebase.

## process.env + dotenv

Node exposes environment variables via `process.env`. In development, the `dotenv` package loads a local `.env` file into it — never commit that file.

## Reading config with fallbacks

Give every variable a sensible default so the app still runs locally without a `.env` file.

```javascript
import 'dotenv/config';

const PORT = process.env.PORT || 3000;
const NODE_ENV = process.env.NODE_ENV || 'development';

app.listen(PORT, () => {
  console.log(`Running in ${NODE_ENV} mode on port ${PORT}`);
});
```