How do you handle environment variables in Node.js?

Environment variables in Node.js are used to configure and customize application behavior based on the runtime environment. They provide a way to pass configuration settings, sensitive information, and runtime parameters to Node.js applications without hardcoding them in the source code.

Node.js applications can access environment variables using the process.env object, which provides a dictionary-like interface to access environment variables. Environment variables are typically set outside the application, either through the command line, configuration files, or environment management tools.

Here’s how you can set and access environment variables in a Node.js application:

Setting Environment Variables:

Environment variables can be set using the command line or a .env file. For example, using the command line:

bash

Copy code

PORT=3000 node app.js

Or using a .env file:

plaintext

Copy code

PORT=3000

Accessing Environment Variables:

In the Node.js application, you can access environment variables using process.env. For example:

javascript

Copy code

const port = process.env.PORT || 3000;

console.log(`Server is running on port ${port}`);

Using dotenv for .env Files:

The dotenv module is commonly used to load environment variables from a .env file into process.env in Node.js applications.

javascript

Copy code

require('dotenv').config();

This allows you to define environment variables in a .env file and load them into your application at runtime.

Environment variables are commonly used to configure database connections, specify API keys and secrets, define application ports, set logging levels, and control feature flags. They help keep applications configurable, portable, and secure across different environments without exposing sensitive information in source code or configuration files.