What is nodemon? | Lecture 8

 

Notes on nodemon Module in Node.js

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What is nodemon?

• nodemon is a utility that helps developers automatically restart a Node.js application whenever file changes are detected.
• It’s a development tool that improves productivity by eliminating the need to manually restart the server after code modifications.

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Key Features of nodemon:

1. Monitors file changes in the application directory.
2. Automatically restarts the Node.js server on file updates.
3. Lightweight and easy to configure.
4. Supports custom configurations and scripts.

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Installing nodemon

1. Globally:
• Installs nodemon globally, making it available for all projects.

o   npm install -g nodemon

• Use the nodemon command from anywhere.
1. Locally (Recommended):
• Installs nodemon as a development dependency.

o   npm install --save-dev nodemon

• Use it in a specific project via npm scripts.

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Using nodemon

1. Basic Usage:
• Replace node with nodemon to start your application.

o   nodemon app.js

2. Running via package.json:
• Add a script in package.json:

o   "scripts": {

o     "start": "node app.js",

o     "dev": "nodemon app.js"

o   }

• Run the script:

o   npm run dev

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How nodemon Works

• nodemon watches for file changes in the current directory and subdirectories.
• When a file changes, it stops the current process and restarts it with the updated code.

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Customizing nodemon Behavior

1. Ignore Specific Files or Directories:
• Use a nodemon.json configuration file or the --ignore flag.
• Example (nodemon.json):

o   {

o     "ignore": ["*.test.js", "node_modules/"]

o   }

• Example (Command Line):

o   nodemon --ignore node_modules app.js

2. Set a Specific File to Watch:
• Use the -w or --watch flag:

o   nodemon -w src app.js

3. Run with a Custom Extension:
• Watch files with specific extensions (e.g., .ts for TypeScript):

o   nodemon --ext js,ts app.js

4. Execute Custom Commands:
• Run a different command instead of restarting the Node.js process:

o   nodemon --exec "npm run build"

5. Delay Restarting:
• Add a delay before restarting the application:

o   nodemon --delay 2.5 app.js

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Creating a Configuration File

• nodemon can be configured using a nodemon.json file in the project root.
• Example:

·        {

·          "watch": ["src"],

·          "ext": "js,json",

·          "ignore": ["node_modules", "logs"],

·          "exec": "node app.js"

·        }

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Advantages of nodemon:

1. Increases development speed by automating restarts.
2. Provides flexibility with configurations and commands.
3. Simple to integrate with any Node.js project.

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Common Commands with nodemon:

1. Start the server:

2.  nodemon app.js

3. Watch specific files:

4.  nodemon -w src app.js

5. Ignore files or directories:

6.  nodemon --ignore node_modules app.js

7. Run with a specific extension:

8.  nodemon --ext js,ts app.js

9. Use a custom delay:

10.nodemon --delay 2.5 app.js

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Best Practices with nodemon:

1. Install nodemon locally for better project-specific control.
2. Use nodemon with npm scripts for standardization in collaborative projects.
3. Exclude unnecessary files or directories to optimize performance.
4. Use configuration files for complex setups.

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Let me know if you'd like a practical example or further assistance!