Introduction

During development, restarting your Node.js server manually after every code change can be tedious. nodemon is a popular development tool that automatically monitors your project files and restarts the server whenever changes are detected, making the development workflow faster and more efficient.

What is nodemon?

nodemon is a command-line utility that wraps your Node.js application. It watches for file changes and automatically restarts the application whenever source files are modified.

Installing nodemon

Install as a Development Dependency

Installing nodemon locally keeps it available only for your project and ensures everyone working on the project uses the same version.

npm install --save-dev nodemon

Install Globally (Optional)

A global installation allows you to use the nodemon command from any project on your system.

npm install -g nodemon

Project Structure

Creating a Simple Server

const http = require("http");

const server = http.createServer((req, res) => {
  res.writeHead(200, {
    "Content-Type": "text/plain"
  });

  res.end("Hello from Node.js!");
});

server.listen(3000, () => {
  console.log("Server running at http://localhost:3000");
});

Running the Application with nodemon

Instead of using the node command, start your application with nodemon.

npx nodemon server.js

If nodemon is installed globally, you can run:

nodemon server.js

What Happens Behind the Scenes?

Adding a Development Script

Instead of typing the full command every time, define a script inside package.json.

{
  "scripts": {
    "dev": "nodemon server.js"
  }
}

Start the development server using:

npm run dev

Watching Additional File Types

By default, nodemon watches JavaScript files. You can configure it to monitor additional file types such as JSON, TypeScript, or template files.

nodemon --ext js,json,ts server.js

Using a nodemon Configuration File

Create a nodemon.json file to avoid repeatedly specifying command-line options.

{
  "watch": ["src"],
  "ext": "js,json",
  "ignore": ["node_modules"],
  "delay": "1000"
}

Configuration Options

Typical Development Workflow

Advantages of Using nodemon

Common Commands

Common Issues

nodemon Command Not Found

This usually occurs when nodemon is not installed globally or is not available in the system path. Using npx nodemon avoids this issue for locally installed versions.

Server Does Not Restart

Frequent Restarts

If your application restarts too often, ignore generated files and build directories such as dist or node_modules using the ignore option.

Comparison: node vs nodemon

Official Resources

nodemon GitHub Repository and nodemon Package on npm

Summary