How to read environment variables in Node.js?

Hello everyone! I'm new to Node.js and trying to figure out environment variables. I have an application that needs to connect to a database. I store the password and username in environment variables to avoid exposing them in the code (especially if I push to GitHub). But I can't figure out how to read them. I created a `.env` file in the project root: ``` DB_USER=myuser DB_PASS=secret123 PORT=3000 ``` In my `app.js` I'm trying to do this: ```javascript const dbUser = process.env.DB_USER; const dbPass = process.env.DB_PASS; const port = process.env.PORT; console.log(dbUser); // undefined console.log(dbPass); // undefined console.log(port); // undefined ``` But the console always prints `undefined`. I've heard that Node.js doesn't read `.env` files by itself. What do I need to do?