Using Nodemon for Automatic Restart in Node.js Development

When developing Node.js applications, manually stopping and restarting the service after each code change wastes time; Nodemon provides automatic file‑watching and hot‑reloading, offering a lightweight alternative to heavier tools like Forever or PM2.

Installation

npm install nodemon -g

Installing globally avoids the need to add Nodemon to each project. On Windows, you may need to add C:\Windows\System32 to the system and user PATH variables and then restart the computer for Nodemon to work correctly.

Basic Usage

Run the following command to start a script and watch for changes:

nodemon app.js

For larger projects, add a script to package.json and start it with:

npm run dev

This will monitor file changes and automatically restart the application.

Configuration

Nodemon looks for a nodemon.json file for custom settings. The configuration can specify which files to ignore (e.g., .git, node_modules), which files to watch, custom restart commands, and environment variables. If no entry file is defined, Nodemon falls back to the main field in package.json or the start script.

Example nodemon.json (illustrated in the original image) includes fields such as restartable, ignore, watch, and env. After creating this file, simply run nodemon to start the service with the defined settings.

Common Issue

If you change the entry file after starting Nodemon (e.g., from before.js to after.js), Nodemon may continue restarting the original file because it caches the entry point; typically the entry file remains constant (e.g., /bin/www), so this situation is rare.

Overall, Nodemon greatly speeds up development by automatically restarting the server on code changes, but it is recommended for use only in development environments.