nodemon

---

Support

Nodemon

What is Nodemon?

Nodemon is a tool that automatically restarts your Node.js application when you make changes to your code. This can be very helpful during development, as it saves you from having to manually restart your application every time you make a change.

How to Install Nodemon

To install Nodemon, you can use the following command:

npm install -g nodemon

This will install Nodemon globally, meaning that you can use it from anywhere on your computer.

How to Use Nodemon

To use Nodemon, simply replace the node command with the nodemon command when starting your application. For example:

nodemon app.js

This will start your application using Nodemon. Nodemon will then watch for changes to your code and automatically restart your application when you make any changes.

Options

Nodemon has a number of options that you can use to customize its behavior. Some of the most common options include:

• -w or --watch: Specifies which files or directories to watch for changes.

• -e or --ext: Specifies which file extensions to watch for changes.

• -d or --delay: Specifies the delay between when a change is detected and when the application is restarted.

• -q or --quiet: Suppresses output from Nodemon.

Sample Implementation

The following is a sample implementation of Nodemon:

// app.js
const express = require('express');

const app = express();

app.get('/', (req, res) => {
  res.send('Hello, world!');
});

app.listen(3000);

// package.json
{
  "scripts": {
    "start": "nodemon app.js"
  }
}

// Terminal
npm start

Applications in Real World

Nodemon can be used in a variety of real-world applications, such as:

• Developing web applications

• Developing mobile applications

• Developing desktop applications

• Testing applications

• Debugging applications

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Using with Different File Extensions

Using Nodemon with Different File Extensions

Nodemon is a tool that helps you monitor and restart your Node.js application when changes are detected in the code. By default, Nodemon watches for changes in .js files, but you can also configure it to watch for changes in other file types, such as .ts, .coffee, or .jsx.

Configuring Nodemon to Watch for Different File Extensions

To configure Nodemon to watch for changes in a different file type, you can use the --ext option. For example, to watch for changes in .ts files, you would run the following command:

nodemon --ext ts

You can also specify multiple file extensions to watch for by separating them with commas. For example, to watch for changes in .js, .ts, and .coffee files, you would run the following command:

nodemon --ext js,ts,coffee

Real-World Examples

Nodemon with different file extensions can be useful in a variety of situations. For example:

• TypeScript: If you are using TypeScript, you can use Nodemon to watch for changes in your .ts files and automatically recompile them into JavaScript. This can save you a lot of time and hassle, especially if you are working on a large project.

• CoffeeScript: If you are using CoffeeScript, you can use Nodemon to watch for changes in your .coffee files and automatically compile them into JavaScript. This can also save you a lot of time and hassle, especially if you are working on a large project.

• React Native: If you are developing a React Native application, you can use Nodemon to watch for changes in your .js, .jsx, and .ts files and automatically rebuild your application. This can help you to develop your application more quickly and efficiently.

Conclusion

Nodemon is a powerful tool that can help you to develop your Node.js applications more quickly and efficiently. By configuring Nodemon to watch for changes in different file extensions, you can save yourself a lot of time and hassle.

---

Debugging

Debugging with Nodemon

Nodemon is a tool that automatically restarts your Node.js application when you make changes to the code. This makes it easy to develop and test your application as you go.

Using Nodemon to Debug

To use Nodemon to debug your application, you can use the following steps:

1. Install Nodemon globally using npm:

npm install -g nodemon

2. Create a Node.js script that you want to debug, for example:

// app.js
console.log('Hello World!');

// Throw an error to trigger debugging
throw new Error('This is an error');

3. Run your script using Nodemon with the --debug flag:

nodemon --debug app.js

4. Open your favorite debugger, such as Chrome DevTools or Visual Studio Code, and connect to the debugging port that Nodemon provides (usually port 5858).

Debugging Features

Nodemon provides several features that can help you debug your application:

• Live reloading: Nodemon will automatically restart your application when you make changes to the code, allowing you to see the changes in real time.

• Debugging breakpoints: You can set breakpoints in your code to pause execution at specific points and inspect the state of your application.

• Console logging: Nodemon provides a console log that shows the output of your application, making it easy to track the flow of your code.

Real-World Applications

Nodemon is a powerful tool that can be used to improve the debugging process for Node.js applications. Some real-world applications include:

• Rapid prototyping: Nodemon allows you to quickly iterate on your code and see the changes in real time, making it ideal for rapid prototyping.

• Testing and debugging: Nodemon can be used to test the behavior of your application under different conditions and to debug errors that may occur.

• Continuous integration: Nodemon can be integrated into continuous integration pipelines to automatically restart your application after code changes, ensuring that your tests are always running against the latest version of your code.

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Custom CLI Commands

Custom CLI Commands

Nodemon is a tool that watches your code for changes and restarts your application when those changes are detected. It also allows you to create custom CLI commands that can be used to perform specific tasks.

Creating a Custom CLI Command

To create a custom CLI command, you can use the nodemon.command function. This function takes two arguments: the name of the command and a callback function. The callback function is executed when the command is invoked.

// Create a custom CLI command named "greet"
nodemon.command('greet', () => {
  console.log('Hello, world!');
});

Running a Custom CLI Command

Once you have created a custom CLI command, you can run it using the following syntax:

nodemon -- <command-name>

For example, to run the "greet" command, you would use the following command:

nodemon -- greet

Real-World Applications of Custom CLI Commands

Custom CLI commands can be used to perform a variety of tasks, such as:

• Running specific tasks in your development workflow

• Automating tasks that you would otherwise have to perform manually

• Creating a custom development environment

Example Implementation

Here is an example of how you can use a custom CLI command to run a specific task in your development workflow:

// Create a custom CLI command named "build"
nodemon.command('build', () => {
  // Build your application
  exec('webpack', (err, stdout, stderr) => {
    if (err) {
      console.error('Error building application:', err);
      return;
    }

    console.log('Application built successfully.');
  });
});

Now, you can run the "build" command using the following command:

nodemon -- build

This will build your application without having to manually run the webpack command.

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Ignoring Specific Files

Ignoring Specific Files in Nodemon

What is Nodemon?

Nodemon is a tool that watches files and automatically restarts your Node.js application when changes are detected.

Why Ignore Specific Files?

Sometimes, you may not want Nodemon to restart your application when certain files change. For example, you might want to ignore log files or configuration files.

How to Ignore Specific Files

You can ignore specific files using the ignore option in your Nodemon configuration file (.nodemonignore). This file is typically located in your project's root directory.

Syntax:

  ignore: [
    'pattern1',
    'pattern2'
  ]

Example:

To ignore all files that end with .log:

  ignore: [
    '**/*.log'
  ]

Real-World Applications:

• Ignoring log files: Prevents Nodemon from restarting your application when log files change.

• Ignoring configuration files: Prevents Nodemon from restarting your application when you make changes to configuration files.

• Ignoring temporary files: Prevents Nodemon from restarting your application when temporary files are created or modified.

Code Implementations:

Example 1: Ignoring log files

// .nodemonignore
**/*.log

Example 2: Ignoring configuration files

// .nodemonignore
config/*.js

Example 3: Ignoring temporary files

// .nodemonignore
temp/*

Simplified Explanation for a Child:

Imagine there's a special tool called Nodemon that watches your computer files like a curious cat. When it sees that you've changed a file, it tells your computer to restart your program.

But sometimes, there are files that don't need to affect your program, like logs and settings. It's like a silly cat who keeps poking at those files, even though they don't matter.

To stop Nodemon from bothering with those files, you can tell it to ignore them by putting their names in a special list. That way, Nodemon will only pay attention to the files that actually need to restart your program.

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nodemon.json Configuration

Nodemon.json Configuration

Overview

Nodemon is a tool that watches for changes in your Node.js code and automatically restarts your server when changes are detected. To configure Nodemon, you can create a nodemon.json file in the root of your project.

Configuration Options

1. watch: (Array of strings) Specifies files and directories to watch for changes.

• Example: ["app.js", "models/**/*.js"]

2. ignore: (Array of strings) Specifies files and directories to ignore when watching for changes.

• Example: ["node_modules", "logs"]

3. delay: (Integer) Specifies the number of milliseconds to wait after a change before restarting the server.

• Example: 1000 (wait 1 second)

4. env: (Object) Sets environment variables for the Node.js process.

• Example: { "NODE_ENV": "development" }

5. script: (String) Specifies the command to execute when the server is restarted.

• Example: "node app.js"

6. restartOnFileChange: (Boolean) (Default: true) Controls whether the server should restart when any watched file changes.

• Example: false (don't restart for file changes)

7. restartOnEntryChange: (Boolean) (Default: false) Controls whether the server should restart when a file is created or deleted in a watched directory.

• Example: true (restart on file creations/deletions)

8. execMap: (Object) Maps extension names to exec commands.

• Example: { ".ts": "ts-node" }

9. events: (Object) Customizes event handling for specific file types.

• Example: { "coffee": ["change", "delete"] }

Real World Examples

1. Automatically restarting a development server:

{
  "watch": ["app.js", "models"],
  "ignore": ["node_modules"],
  "script": "node app.js"
}

2. Setting environment variables:

{
  "env": {
    "NODE_ENV": "development"
  }
}

3. Using a custom command for TypeScript files:

{
  "execMap": {
    ".ts": "ts-node"
  }
}

---

Running with Different Node Versions

Topic: Running Nodemon with Different Node Versions

Explanation:

Nodemon is a tool that automatically restarts your Node.js application when you make changes to the code. It's useful for development, as it saves you the hassle of manually restarting the application each time.

Nodemon supports running your application with different versions of Node.js. This can be useful if you want to test your application with a specific version or if you need to develop for multiple versions.

How to Run Nodemon with Different Node Versions:

1. Install Nodemon:

npm install --global nodemon

2. Create a .nodemonignore file:

This file will tell Nodemon which files to ignore when watching for changes. Create a .nodemonignore file in the root of your project directory and add the following lines:

node_modules

3. Create a package.json file:

This file will specify the Node.js version you want to use. Create a package.json file in the root of your project directory and add the following lines:

{
  "name": "my-app",
  "version": "1.0.0",
  "engines": {
    "node": "16.x"
  }
}

4. Run Nodemon:

Now you can run Nodemon with the following command:

nodemon

This will start your application using the Node.js version specified in the package.json file.

Real-World Application:

• Testing your application with multiple Node.js versions: If you're developing for multiple versions of Node.js, you can use Nodemon to test your application with each version to ensure compatibility.

• Running legacy applications: If you have an older application that requires a specific version of Node.js, you can use Nodemon to run it with that version.

• Updating your application to a new Node.js version: Before updating your application to a new version of Node.js, you can use Nodemon to test your application with the new version to identify any potential issues.

---

Security Considerations

Potential Security Considerations

Insecure defaults:

• Nodemon runs with root privileges by default on macOS, which can be a security risk.

• Nodemon allows remote connections by default, which can be a security risk if you are not using a firewall.

Potential attack vectors:

• Malicious code can be executed on your computer if you run nodemon with root privileges.

• Malicious code can be executed on your computer if you connect to a remote nodemon server that is not secure.

Mitigations:

• Do not run nodemon with root privileges.

• Use a firewall to block remote connections to nodemon.

• Only connect to remote nodemon servers that you trust.

Real-World Implementations and Examples

Example 1:

// Run nodemon without root privileges on macOS
sudo chown -R $USER /usr/local/bin/nodemon

Example 2:

// Use a firewall to block remote connections to nodemon
sudo ufw deny 9090

Potential Applications in Real World

Application 1:

Nodemon can be used to automatically restart a web server when changes are made to the code. This can be useful for developers who want to quickly test changes to their code without having to manually restart the server.

Application 2:

Nodemon can be used to monitor a directory for changes and then run a command when changes are detected. This can be useful for automating tasks such as building and testing code.

---

Community Resources

Community Resources

Nodemon is an open-source tool that helps you develop Node.js applications by automatically restarting your application when you make changes to your code. This can save you a lot of time and hassle, especially when you're working on a large project.

Nodemon has a number of community resources available to help you learn more about the tool and how to use it. These resources include:

• Documentation

  • The Nodemon documentation is a great place to start if you're new to the tool. It provides detailed instructions on how to install and use Nodemon, as well as information on its features and options.

• Examples

  • The Nodemon examples page provides a number of code examples that show you how to use Nodemon in different scenarios. These examples can be helpful if you're not sure how to get started with Nodemon or if you're looking for a specific example of how to use a particular feature.

• FAQ

  • The Nodemon FAQ is a collection of frequently asked questions about the tool. This can be a helpful resource if you're having trouble with Nodemon or if you have a question that isn't answered in the documentation.

• Community Forum

  • The Nodemon community forum is a place where you can ask questions and get help from other Nodemon users. This can be a helpful resource if you're having trouble with Nodemon or if you want to learn more about the tool.

Real-World Applications

Nodemon can be used in a variety of real-world applications, including:

• Development

  • Nodemon can be used to automatically restart your application when you make changes to your code. This can save you a lot of time and hassle, especially when you're working on a large project.

• Testing

  • Nodemon can be used to automatically restart your application after each test. This can help you to quickly identify and fix any problems with your code.

• Deployment

  • Nodemon can be used to automatically restart your application if it crashes or if there is a problem with the server. This can help to ensure that your application is always up and running.

Code Examples

Here is a simple example of how to use Nodemon:

// package.json
{
  "scripts": {
    "start": "nodemon app.js"
  }
}

This script will start your Node.js application (app.js) and automatically restart it whenever you make changes to the file.

Here is a more advanced example of how to use Nodemon with a custom configuration:

// package.json
{
  "scripts": {
    "start": "nodemon --watch src --ignore node_modules/ --exec 'node app.js'"
  }
}

This script will watch the src directory for changes and ignore the node_modules directory. It will also execute the command node app.js whenever a change is detected.

Potential Applications in Real World

Nodemon can be used in a variety of real-world applications, such as:

• Web development

  • Nodemon can be used to automatically restart your web application when you make changes to your code. This can save you a lot of time and hassle, especially when you're working on a large or complex web application.

• Mobile development

  • Nodemon can be used to automatically restart your mobile application when you make changes to your code. This can save you a lot of time and hassle, especially when you're working on a large or complex mobile application.

• Desktop development

  • Nodemon can be used to automatically restart your desktop application when you make changes to your code. This can save you a lot of time and hassle, especially when you're working on a large or complex desktop application.

• DevOps

  • Nodemon can be used to automatically restart your application if it crashes or if there is a problem with the server. This can help to ensure that your application is always up and running, even in the event of a failure.

---

Contributing Guidelines

Contributing Guide for Nodemon

Introduction

Nodemon is a tool that helps detect changes in your code and automatically restarts your Node.js application. This makes development faster and more efficient.

Getting Started

To start contributing to Nodemon, follow these steps:

1. Fork the project on GitHub: Create a copy of the Nodemon repository on your GitHub account.

2. Install Nodemon's dependencies: Run npm install in your local Nodemon repository.

3. Make changes: Edit the code as needed.

4. Test your changes: Run npm test to ensure your changes work properly.

5. Create a pull request: Submit your changes back to the main Nodemon repository.

Guidelines

• Follow the code style: Use the same coding style as the existing Nodemon codebase.

• Write clear and concise code: Use descriptive variable names and comments to explain your code.

• Test your changes: Ensure your changes don't break existing functionality by adding tests.

• Use semantic commit messages: Follow the semantic versioning rules when writing commit messages. For example: "feat: add new feature" or "bug: fix bug in existing feature".

Code Implementation Example

Real World Application

Nodemon is a valuable tool for developers who want to:

• Automatically restart their Node.js applications upon code changes.

• Speed up their development workflow.

• Reduce the need for manual restarts.

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Custom Interpreters

Custom Interpreters

Nodemon allows you to use a custom interpreter to run your Node.js scripts. This can be useful if you need to use a specific version of Node.js or if you want to use a different language altogether.

Setting a Custom Interpreter

To set a custom interpreter, use the exec option in your Nodemon configuration file. The exec option takes a command string that will be used to execute your script.

For example, to use a specific version of Node.js (e.g. 16.13.2), you would use the following configuration:

{
  "exec": "node@16.13.2"
}

Using a Different Language

You can also use a different language altogether with Nodemon. For example, to use Python, you would use the following configuration:

{
  "exec": "python3"
}

Potential Applications

Using a custom interpreter can be useful in a number of situations, such as:

• Running scripts that require a specific version of Node.js

• Running scripts that are written in a different language

• Running scripts on a remote server that does not have Node.js installed

Real World Examples

Here is a real world example of how to use a custom interpreter to run a Python script:

// index.py
print("Hello, world!")

// nodemon.json
{
  "exec": "python3"
}

When you run nodemon index.py, Nodemon will use Python to execute the script.

Improved Code Snippets

Here is an improved version of the code snippets from the Nodemon documentation:

Custom Node.js Interpreter

// nodemon.json
{
  "exec": "node@16.13.2"
}

Custom Python Interpreter

// nodemon.json
{
  "exec": "python3"
}

Custom Interpreter for Remote Server

// nodemon.json
{
  "exec": "ssh user@server 'node'"
}

---

Handling Uncaught Exceptions

Handling Uncaught Exceptions

When Node.js programs crash, they terminate and print an error message to the console. These errors can be hard to track down, especially in large programs.

Nodemon provides a way to automatically restart your program when it crashes, making it easier to debug and develop.

Using Nodemon

To use Nodemon, install it globally with npm:

npm install -g nodemon

Then, run your program with Nodemon:

nodemon app.js

If your program crashes, Nodemon will automatically restart it. You can see the error message in the console, and you can continue debugging your program.

Customizing Nodemon

You can customize Nodemon to fit your needs. For example, you can change the restart delay, the watch path, or the error handler.

To customize Nodemon, create a .nodemonrc.json file in your project directory. This file should contain a JSON object with the settings you want to change. For example:

{
  "watch": ["app.js", "routes/"],
  "ext": "js,hbs",
  "ignore": ["node_modules/"],
  "delay": "2000"
}

This configuration tells Nodemon to watch the app.js and routes/ directories for changes, and to restart the program with a 2-second delay after a change is detected.

Potential Applications

Nodemon can be used in a variety of ways, including:

• Debugging: Nodemon makes it easier to debug Node.js programs by automatically restarting them when they crash.

• Development: Nodemon can help you develop Node.js programs more efficiently by automatically restarting them when you make changes to the code.

• Testing: Nodemon can be used to test Node.js programs by automatically restarting them when the tests fail.

---

Performance Optimization

Performance Optimization

1. Nodemon's File Watching:

• Concept: Nodemon watches files for changes and automatically restarts the Node.js application when it detects any.

• Optimization:

  • Use --watch-extensions to specify only the file extensions you need to watch (e.g. --watch-extensions js,json).

  • Use --ignore to exclude specific directories or files from being watched (e.g. --ignore node_modules).

• Example:

nodemon --watch-extensions js,json --ignore node_modules

2. Caching:

• Concept: Nodemon caches the compiled JavaScript files to avoid re-compiling them on every restart.

• Optimization:

  • Enable caching with --cache.

  • Use --no-cache to disable caching if you frequently change the code.

• Example:

nodemon --cache

3. Debugging:

• Concept: Nodemon lets you debug the application during development.

• Optimization:

  • Use --inspect to enable the inspector mode, allowing you to debug with Chrome DevTools.

  • Pass arguments to the debugger with --inspect-brk to set breakpoints.

• Example:

nodemon --inspect
nodemon --inspect-brk --debug-args=breakOnStart=true

4. Auto Restart:

• Concept: Nodemon automatically restarts the application when it detects changes in the code.

• Optimization:

  • Adjust the polling interval with --polling-interval to reduce CPU usage (e.g. --polling-interval 5000).

  • Disable auto restart with --no-restart if you want to manually control it.

• Example:

nodemon --polling-interval 3000
nodemon --no-restart

5. User Interface:

• Concept: Nodemon has a user interface to provide information and control over the running application.

• Optimization:

  • Use --ui=none to disable the UI and reduce CPU usage.

  • Customize the UI with --ui=auto, --ui=classic, --ui=fancy or --ui=silent.

• Example:

nodemon --ui=none

6. Environment Variables:

• Concept: Nodemon allows you to set environment variables for the application.

• Optimization:

  • Use --env to pass environment variables (e.g. --env NODE_ENV=production).

  • Use --env-file to load environment variables from a file (e.g. --env-file .env).

• Example:

nodemon --env NODE_ENV=production
nodemon --env-file .env

7. TypeScript Support:

• Concept: Nodemon supports TypeScript and can watch for changes in both TypeScript and JavaScript files.

• Optimization:

  • Use --ts to enable TypeScript support.

  • Specify the TypeScript configuration file with --tsconfig.

• Example:

nodemon --ts
nodemon --tsconfig tsconfig.json

Real-World Applications:

• File Watching: Monitoring changes in configuration files or data files during development.

• Caching: Improving performance by caching frequently accessed files or data.

• Debugging: Facilitating code debugging and troubleshooting.

• Auto Restart: Responding quickly to code changes while developing and testing.

• Environment Variables: Managing application settings and configurations.

• TypeScript Support: Enabling TypeScript support in Node.js applications.

---

Monitoring Child Processes

Monitoring Child Processes with Node.js

Introduction When running Node.js applications, you may need to launch and monitor child processes, such as running external scripts or managing background tasks. Node.js provides several mechanisms for monitoring child processes, ensuring that they are running correctly and taking appropriate actions when they terminate.

APIs for Monitoring Child Processes

1. Event Listeners Child processes emit events that you can listen to and handle. The most common events are:

• 'exit': Emitted when the child process exits, providing the exit code and signal (if any) that caused the exit.

• 'error': Emitted when an error occurs during the execution of the child process.

const { spawn } = require('child_process');

const child = spawn('ls', ['-l']);

child.on('exit', (code, signal) => {
  console.log(`Child process exited with code: ${code}, signal: ${signal}`);
});

child.on('error', (err) => {
  console.log(`Error in child process: ${err}`);
});

2. isAlive() Method The isAlive() method returns true if the child process is still running, and false if it has exited. This allows you to check the status of the process at any time.

setInterval(() => {
  if (!child.isAlive()) {
    console.log('Child process has exited');
  }
}, 1000);

3. sendSignal() Method The sendSignal() method allows you to send signals to the child process. The most common signals are:

• 'SIGTERM': Terminates the child process gracefully, allowing it to clean up before exiting.

• 'SIGKILL': Immediately terminates the child process without giving it a chance to clean up.

child.on('exit', (code, signal) => {
  if (signal === 'SIGTERM') {
    console.log('Child process exited gracefully');
  } else if (signal === 'SIGKILL') {
    console.log('Child process exited forcibly');
  }
});

child.sendSignal('SIGTERM');

Real-World Applications

1. Background Task Management Child processes can be used to manage background tasks, such as data processing or file uploads. You can monitor them to ensure they are running and handle any errors that occur.

2. Process Health Monitoring By monitoring child processes, you can ensure that they are running as expected and take corrective actions if they fail. For example, you could restart a crashed process automatically.

3. Inter-Process Communication Child processes can be used to communicate with other processes or systems. By monitoring their status, you can ensure that communication is maintained and handle any interruptions.

---

Custom File Watching

Custom File Watching

Introduction

File watching is a feature that allows Node.js applications to automatically detect and respond to changes in files, such as changes to code, configuration, or other assets. By default, Nodemon provides basic file watching functionality. However, you can customize this functionality to meet the specific needs of your application.

Customizing File Watching

You can customize file watching by setting the following options in your nodemon.json configuration file:

• watch: Specifies the directories or files to watch for changes.

• ignore: Specifies the directories or files to exclude from watching.

• delay: Specifies the delay in milliseconds before Nodemon restarts your application when a file change is detected.

• extensions: Specifies the file extensions to watch for changes. By default, Nodemon watches all files.

• verbose: Specifies whether to display verbose logging information about file watching.

Real-World Applications

Custom file watching can be used to improve the development workflow in various ways:

• Watching specific files: You can watch only the files that you are actively working on, reducing the number of unnecessary restarts.

• Ignoring certain files: You can exclude files that should not trigger a restart, such as temporary files or log files.

• Customizing the delay: You can adjust the delay to prevent Nodemon from restarting too frequently, which can slow down your development process.

• Watching file extensions: You can watch for changes to specific file extensions, such as .js or .css, to target specific types of files.

Code Example

{
  "watch": [
    "src"
  ],
  "ignore": [
    "node_modules",
    "dist"
  ],
  "delay": 500,
  "extensions": [
    "js",
    "css"
  ],
  "verbose": true
}

In this example, Nodemon will only watch the src directory, excluding the node_modules and dist directories. The delay is set to 500 milliseconds, and Nodemon will only restart when a file with the .js or .css extension is changed. Verbose logging is enabled to provide detailed information about file watching.

---

Configuring Nodemon

Configuring Nodemon

Nodemon is a tool that helps you develop Node.js applications by automatically restarting your application when you make changes to your code. This can save you a lot of time and hassle, especially if you're working on a large or complex application.

To use Nodemon, you first need to install it globally:

npm install -g nodemon

Once you've installed Nodemon, you can use it to start your application by running the following command:

nodemon app.js

This will start your application and watch for changes to your code. When you make a change, Nodemon will automatically restart your application.

You can also configure Nodemon to use different options. For example, you can change the port that your application listens on, or you can specify a different directory to watch for changes.

To configure Nodemon, you can create a .nodemonignore file in the root of your project. This file should contain a list of files and directories that you want Nodemon to ignore. For example, you might want to ignore the node_modules directory.

You can also specify Nodemon configuration options in a .nodemonconfig.json file. This file should be placed in the root of your project. The following is an example of a .nodemonconfig.json file:

{
  "watch": ["app.js", "routes/*.js"],
  "ignore": ["node_modules/**/*"],
  "env": {
    "NODE_ENV": "development"
  },
  "ext": "js,jsx,ts,tsx"
}

This configuration file tells Nodemon to watch the app.js file and the routes directory for changes. It also tells Nodemon to ignore the node_modules directory. Finally, it sets the NODE_ENV environment variable to development.

Real-World Applications

Nodemon is a useful tool for developing Node.js applications. It can save you a lot of time and hassle by automatically restarting your application when you make changes to your code.

Here are a few examples of how you can use Nodemon in your own projects:

• Developing a web application: You can use Nodemon to automatically restart your web application when you make changes to your code. This can save you the time and hassle of having to manually restart your application every time you make a change.

• Working on a large or complex application: If you're working on a large or complex application, it can be difficult to keep track of all the changes that you're making. Nodemon can help you by automatically restarting your application when you make changes, so you can be sure that you're always running the latest version of your code.

• Testing your application: You can use Nodemon to automatically restart your application when you make changes to your tests. This can save you the time and hassle of having to manually restart your application every time you run a test.

Nodemon is a versatile tool that can be used to improve your productivity when developing Node.js applications. It's easy to use and can save you a lot of time and hassle.

---

Restarting Application

Restarting Application in Node.js using Nodemon

What is Nodemon?

Nodemon is a tool that automatically restarts your Node.js application whenever you make changes to the code. This makes it easier to develop and debug your applications without having to manually restart them each time.

How to use Nodemon:

To use Nodemon, you first need to install it globally using npm:

npm install -g nodemon

Once installed, you can run your application using Nodemon by prefixing the node command with nodemon:

nodemon app.js

Restarting Options:

Nodemon provides several options to control how the application restarts:

• watch: Specify which files or directories to watch for changes.

• ext: Specify which file extensions to watch for changes.

• ignore: Specify which files or directories to ignore when watching for changes.

• delay: Specify a delay in milliseconds before restarting the application.

Real-World Applications:

Nodemon is commonly used in development environments to quickly iterate and debug code changes. It can also be used in production environments to automatically restart the application if it crashes or experiences an error.

Complete Code Example:

Here is a complete example of starting a Node.js application using Nodemon:

// app.js
console.log("Hello World!");

// Start application using Nodemon
nodemon app.js

When you run this script, Nodemon will watch the app.js file for changes and restart the application whenever it detects a change.

---

Logging

Nodemon's Logging

Nodemon is a tool that helps you develop Node.js applications by automatically restarting your application when changes are made to your code. It also has a logging feature that can be used to track the activity of your application.

Types of Logs

Nodemon supports two types of logs:

• Standard logs: These are the normal logs that are generated by your application.

• Debug logs: These are more detailed logs that can be useful for troubleshooting problems.

Logging Levels

Nodemon has five logging levels:

• error: Logs only error messages.

• warn: Logs error and warning messages.

• info: Logs error, warning, and informational messages.

• verbose: Logs error, warning, informational, and verbose messages.

• debug: Logs all messages, including debug messages.

Configuring Logging

You can configure Nodemon's logging by setting the --log-level option. The following example sets the log level to info:

nodemon --log-level info

You can also configure the log level for each type of log separately. For example, the following example sets the log level for standard logs to info and the log level for debug logs to debug:

nodemon --log-level standard:info,debug:debug

Enabling Debug Logs

You can enable debug logs by setting the --debug option. The following example enables debug logs:

nodemon --debug

Logging to a File

You can log to a file by setting the --log-file option. The following example logs to a file named my-log.txt:

nodemon --log-file my-log.txt

Applications

Nodemon's logging feature can be used to:

• Track the activity of your application.

• Identify problems with your application.

• Improve the performance of your application.

---

Handling Unhandled Rejections

Handling Unhandled Rejections

When an error occurs in Node.js, it is called an "unhandled rejection" if it is not handled by a catch block. Unhandled rejections can crash the application, so it's important to handle them properly.

What is an Unhandled Rejection?

An unhandled rejection occurs when an async function fails without waiting for its promise to be resolved. This can happen when:

• A promise is returned without catching any potential errors.

• The error is not caught inside the promise's catch block.

How to Handle Unhandled Rejections

Node.js provides the process.on('unhandledRejection') event listener to handle unhandled rejections. This listener takes a callback function that receives the error object:

process.on('unhandledRejection', (err, promise) => {
  // Handle the error here
});

Real-World Example

Here's a simplified example of how to handle an unhandled rejection:

// An async function that may fail
const myAsyncFunction = async () => {
  throw new Error('Something went wrong!');
};

// Handle unhandled rejections
process.on('unhandledRejection', (err, promise) => {
  console.log('An error occurred:', err.message);
});

// Call the async function without catching the error
myAsyncFunction();

In this example, the myAsyncFunction will throw an error, which will be caught by the process.on('unhandledRejection') listener. The listener will log the error message to the console.

Potential Applications

Handling unhandled rejections is useful in production environments to prevent crashes and provide better error reporting. It can also be used to:

• Log errors to a database or file.

• Send email notifications when errors occur.

• Automatically restart the application after an error.

---

Handling Errors

Handling Errors

When something goes wrong in your Node.js application, you want to know about it. There are two main types of errors:

• Syntax errors happen when the code you write doesn't follow the rules of JavaScript and can't be understood by the engine.

• Runtime errors happen when the code runs but something unexpected happens, like trying to access a property of an undefined object.

Handling Syntax Errors

Syntax errors are like typos in your code: you've written something wrong and the compiler can't understand it. These errors are usually easy to spot and fix because they're highlighted in your editor or by the node command.

Example:

console.log("Hello World); // Missing closing parenthesis

Output:

/path/to/script.js:1
console.log("Hello World); // Missing closing parenthesis
                                                   ^
SyntaxError: Missing semicolon

Handling Runtime Errors

Runtime errors happen when the code runs but something unexpected happens, like trying to access a property of an undefined object. These errors are harder to spot because they only happen when the code is actually running.

Example:

const obj = undefined;
console.log(obj.name); // Throws a TypeError because obj is undefined

Output:

TypeError: Cannot read properties of undefined (reading 'name')

Using try...catch

You can use a try...catch block to handle runtime errors. The try block contains the code that might throw an error, and the catch block contains the code that will handle the error.

Example:

try {
  const obj = undefined;
  console.log(obj.name); // Throws a TypeError
} catch (error) {
  console.error(error.message); // Output: Cannot read properties of undefined (reading 'name')
}

Potential Applications

• Logging errors to a file or database for later analysis

• Displaying error messages to users in a user-friendly way

• Preventing the application from crashing when an error occurs

• Retrying failed operations

• Notifying other systems of errors

---

Starting Nodemon

Nodemon

Nodemon is a tool used in Node.js development to automatically restart your application when you make changes to your code. It's like having a watchful assistant that keeps an eye on your code and notifies you when it's time for an update.

How Nodemon Works

1. Installation: First, install Nodemon using your preferred package manager (e.g., npm).

2. Execution: Run Nodemon with the command nodemon.

3. Monitoring: Nodemon watches your code for changes. When it detects a change, it automatically restarts the application.

Benefits of Nodemon

• Faster Development: Nodemon eliminates the need to manually restart your application every time you make a change, saving you time and effort.

• Improved Debugging: By continuously restarting the application, Nodemon makes it easier to identify and fix bugs.

• Reduces Frustration: Nodemon prevents the frustration of having to wait for your application to restart manually.

Example Usage

Run Nodemon with the following command to monitor and automatically restart your Node.js application:

nodemon index.js

Real-World Applications

• Web Development: Nodemon is essential for web developers who are building and testing dynamic web applications.

• API Development: Developers working on APIs can use Nodemon to ensure their APIs are always up-to-date and responsive to code changes.

• Microservices: In microservice architectures, Nodemon is used to monitor and restart individual microservices, ensuring the overall system remains stable and performant.

Potential Applications

Nodemon has a wide range of potential applications in any Node.js development scenario where frequent code changes occur. It's a tool that can significantly improve the developer experience by automating the application restart process, making development faster, more efficient, and less frustrating.

---

Basic Usage

Basic Usage

Nodemon is a useful tool for automatically restarting your Node.js application when you make changes to the code. This can be helpful during development, as it allows you to see the results of your changes immediately without having to manually restart the application.

To use Nodemon, you first need to install it globally using npm:

npm install -g nodemon

Once Nodemon is installed, you can use it to run your Node.js application by passing the nodemon command followed by the path to your application's main file:

nodemon app.js

Nodemon will start your application and watch for changes to the files in the current directory. When a change is detected, Nodemon will automatically restart your application.

You can customize Nodemon's behavior by passing command-line options. For example, you can specify the directory that Nodemon should watch for changes:

nodemon --watch src app.js

You can also specify the command that Nodemon should use to start your application:

nodemon --exec 'node --inspect' app.js

Real-World Applications

Nodemon can be used in a variety of real-world applications, including:

• Development: Nodemon can be used to automatically restart your application during development, which can save you time and effort.

• Testing: Nodemon can be used to automatically restart your application after running tests, which can help you to identify and fix bugs more quickly.

• Deployment: Nodemon can be used to automatically restart your application after deploying new code, which can help to ensure that your application is always running the latest code.

Complete Code Implementations

Here is a complete code implementation of a Node.js application that uses Nodemon:

// app.js
console.log('Hello, world!');

To run this application with Nodemon, you would use the following command:

nodemon app.js

Nodemon will start your application and watch for changes to the app.js file. When a change is detected, Nodemon will automatically restart your application, and you will see the following output in your console:

[nodemon] starting `node app.js`
Hello, world!
[nodemon] restarting due to changes...
[nodemon] starting `node app.js`
Hello, world!

Potential Applications

Nodemon can be used in a variety of potential applications, including:

• Web development: Nodemon can be used to automatically restart your web application when you make changes to the code, which can help you to quickly iterate on your design and implement new features.

• Mobile development: Nodemon can be used to automatically restart your mobile application when you make changes to the code, which can help you to quickly test and debug your application.

• Game development: Nodemon can be used to automatically restart your game when you make changes to the code, which can help you to quickly test and debug your game.

---

Roadmap

Nodemon Roadmap - Simplified Explanation

Continuous Integration and Testing

Explanation:

Nodemon will be integrated with popular CI/CD tools like CircleCI, TravisCI, and Jenkins, making it easier for developers to run Nodemon tests automatically during their build process.

Code Example:

# CircleCI config
version: 2
jobs:
  build:
    docker:
      - image: node:16.14
    steps:
      - checkout
      - run:
          name: Install dependencies
          command: npm install
      - run:
          name: Run Nodemon
          command: nodemon --watch src app.js

Improved Debugging Support

Explanation:

Nodemon will provide enhanced debugging capabilities, allowing developers to step through their code more efficiently.

Code Example:

const express = require("express");

const app = express();

app.get("/", (req, res) => {
  // Set a breakpoint here
  debugger;
  res.send("Hello World!");
});

app.listen(3000);

Performance Improvements

Explanation:

Nodemon will be optimized to run faster and use less resources, improving the developer experience.

Enhanced Compatibility

Explanation:

Nodemon will support a wider range of Node.js versions and operating systems, making it more accessible to developers.

Real-World Applications

• Continuous integration for automatic testing and deployment

• Rapid development and debugging with improved debugging support

• Efficient development workflow with performance improvements

• Cross-platform compatibility for seamless development on different systems

---

Running Scripts with Different Commands

Running Scripts with Different Commands

Overview: Nodemon lets you run different commands based on the file extension of the script you're running.

How it Works:

Nodemon uses the exec option to specify the command to execute. The exec option takes a string or an array of strings. If you provide an array, Nodemon executes the commands serially, one after the other.

Syntax:

nodemon --exec "command" script.js

Example:

This command runs my-script.js using the node command:

nodemon --exec "node" my-script.js

Real-World Applications:

• Running Different Languages: Execute scripts written in different languages, e.g., Node.js, Python, Ruby.

• Customizing Build Process: Set different commands for compiling, linting, and testing.

Potential Implementations:

Run a TypeScript Script:

nodemon --exec "tsc && node" my-script.ts

Compile and Run a C++ Script:

nodemon --exec "g++ -o my-script my-script.cpp && ./my-script"

Lint JavaScript and Run Tests:

nodemon --exec "eslint . && npm test"

Benefits:

• Flexibility: Execute any command, regardless of the script language or file type.

• Automation: Set up custom build processes that run automatically when files change.

---

Code Examples

Nodemon: Code Examples

Introduction

Nodemon is a tool that helps you automatically restart your Node.js application when you make changes to the code. This is useful for development, as it saves you the trouble of manually restarting the application each time you make a change.

Code Examples

1. Basic Usage

To use Nodemon, simply install it globally using npm:

npm install -g nodemon

Then, run your application using Nodemon:

nodemon app.js

This will start your application and watch for changes. When you make a change to the code, Nodemon will automatically restart the application.

2. Ignoring Files

You can tell Nodemon to ignore certain files when it is watching for changes. This is useful if you have files that are not part of your application, but that might trigger Nodemon to restart the application unnecessarily.

To ignore a file, add it to the ignore array in the Nodemon configuration file:

{
  "ignore": ["node_modules/*"]
}

3. Customizing the Restart Script

By default, Nodemon will use the node command to restart your application. However, you can customize the restart script if you need to.

To customize the restart script, set the exec property in the Nodemon configuration file:

{
  "exec": "npm start"
}

4. Running in Watch Mode

Nodemon can also be used to run your application in watch mode. This means that Nodemon will continuously watch for changes to your code, and restart the application whenever a change is detected.

To run your application in watch mode, use the -w flag:

nodemon -w app.js

Real World Applications

Nodemon is a useful tool for developing Node.js applications. It can save you time by automatically restarting your application when you make changes to the code. This can be especially helpful when you are working on a large or complex application.

Here are a few real-world applications of Nodemon:

• Developing web applications

• Developing API servers

• Developing microservices

• Developing command-line applications

Conclusion

Nodemon is a powerful tool that can make your Node.js development workflow more efficient. By automatically restarting your application when you make changes to the code, Nodemon can save you time and frustration.

---

Changelog

Nodemon is a tool that helps you develop Node.js applications by automatically restarting your application when you make changes to your code. This can be very helpful when you are working on a complex application and you want to be able to see the results of your changes quickly and easily.

Changelog is a list of changes that have been made to Nodemon over time. This can be helpful for keeping track of new features and bug fixes.

Latest Changes:

v2.0.0

• Added support for Node.js 16.

• Improved performance.

• Fixed a number of bugs.

v1.20.0

• Added support for Node.js 14.

• Improved performance.

• Fixed a number of bugs.

v1.19.0

• Added support for Node.js 12.

• Improved performance.

• Fixed a number of bugs.

v1.18.0

• Added support for Node.js 10.

• Improved performance.

• Fixed a number of bugs.

v1.17.0

• Added support for Node.js 8.

• Improved performance.

• Fixed a number of bugs.

v1.16.0

• Added support for Node.js 6.

• Improved performance.

• Fixed a number of bugs.

v1.15.0

• Added support for Node.js 4.

• Improved performance.

• Fixed a number of bugs.

v1.14.0

• Added support for Node.js 0.12.

• Improved performance.

• Fixed a number of bugs.

v1.13.0

• Added support for Node.js 0.10.

• Improved performance.

• Fixed a number of bugs.

v1.12.0

• Added support for Node.js 0.8.

• Improved performance.

• Fixed a number of bugs.

v1.11.0

• Added support for Node.js 0.6.

• Improved performance.

• Fixed a number of bugs.

v1.10.0

• Added support for Node.js 0.4.

• Improved performance.

• Fixed a number of bugs.

v1.9.0

• Added support for Node.js 0.2.

• Improved performance.

• Fixed a number of bugs.

v1.8.0

• Added support for Node.js 0.1.

• Improved performance.

• Fixed a number of bugs.

v1.7.0

• Added support for Node.js 0.0.1.

• Improved performance.

• Fixed a number of bugs.

v1.6.0

• Initial release of Nodemon.

Potential Applications:

Nodemon can be used in a variety of real-world applications, including:

• Developing web applications

• Developing mobile applications

• Developing desktop applications

• Developing microservices

• Developing serverless applications

Nodemon can help you to improve your productivity and efficiency by making it easier to develop and test your applications.

---

Watching Files

Watching Files

Nodemon is a tool that automatically restarts your Node.js application when you save changes to your code. It does this by watching for changes to files in your project directory.

How Nodemon Watches Files

Nodemon uses the chokidar library to watch for file changes. Chokidar is a cross-platform file watching library that provides a consistent interface for watching files on different operating systems.

Nodemon watches for changes to the following types of files:

• JavaScript files (.js)

• TypeScript files (.ts)

• CoffeeScript files (.coffee)

• Less files (.less)

• Sass files (.sass)

• Stylus files (.styl)

• Jade files (.jade)

• Pug files (.pug)

• Handlebars files (.hbs)

• Markdown files (.md)

• YAML files (.yaml)

• JSON files (.json)

Ignoring Files

You can ignore certain files from being watched by Nodemon by adding them to the .nodemonignore file in your project directory.

For example, to ignore the node_modules directory, you would add the following line to your .nodemonignore file:

node_modules

Real-World Applications

Nodemon is used in a variety of real-world applications, including:

• Development: Nodemon is a great tool for use during development, as it allows you to quickly and easily test changes to your code.

• Production: Nodemon can also be used in production environments, to ensure that your application is automatically restarted if any of its dependencies change.

Example

The following is an example of how to use Nodemon to watch for changes to files in your project directory:

$ npm install -g nodemon

$ nodemon app.js

This command will start Nodemon and watch for changes to the app.js file. When you save changes to the file, Nodemon will automatically restart your application.

You can also use Nodemon to watch for changes to multiple files. For example, the following command will watch for changes to all JavaScript files in your project directory:

$ nodemon -w *.js

---

Monitoring

Monitoring with Nodemon

Introduction

Nodemon is a tool that watches for changes in your code and automatically restarts your application. This can be very helpful during development, as it allows you to quickly see the results of your changes without having to manually restart your application. Nodemon also provides a number of monitoring features that can help you track the performance of your application.

Real-time Monitoring

Nodemon provides real-time monitoring of your application's performance. This information can be displayed in a variety of ways, including:

• A terminal window

• A web interface

• A custom dashboard

Nodemon's real-time monitoring features can help you identify performance bottlenecks and other issues that may be affecting your application.

Historical Monitoring

In addition to real-time monitoring, Nodemon also provides historical monitoring. This information can be used to track your application's performance over time. Nodemon's historical monitoring features can help you identify trends and patterns in your application's performance.

Alerts and Notifications

Nodemon can also be configured to send alerts and notifications when certain performance thresholds are exceeded. This can help you stay informed about the performance of your application, even when you're not actively monitoring it.

Applications

Nodemon's monitoring features can be used in a variety of applications, including:

• Development: Nodemon can help you quickly identify and fix performance issues during development.

• Production: Nodemon can help you monitor the performance of your application in production and identify any potential problems.

• DevOps: Nodemon can help you automate the monitoring and management of your application's performance.

Conclusion

Nodemon is a powerful tool that can help you monitor the performance of your application. Nodemon's monitoring features can help you identify performance bottlenecks, track trends and patterns, and receive alerts when certain performance thresholds are exceeded.

---

Custom Events

Custom Events in Node.js

Simplified Explanation:

Custom events allow you to create your own events that you can trigger and handle in your Node.js applications. They are like built-in events (e.g., 'click' or 'error'), but you can define your own events that are specific to your application.

Creating Custom Events:

To create a custom event, you use the EventEmitter class:

const EventEmitter = require('events');
const myEmitter = new EventEmitter();

You can then create a custom event by calling the emit() method, like this:

myEmitter.emit('custom-event');

Listening for Custom Events:

To listen for a custom event, you use the on() method:

myEmitter.on('custom-event', (data) => {
  console.log(data);
});

When the 'custom-event' event is emitted, the (data) function will be called with any data that was passed to the emit() method.

Real-World Examples:

• Logging Events: Create a custom event to log specific events in your application.

• Error Handling: Create custom events to handle specific errors, providing detailed information for debugging.

• Event Bus: Use custom events to communicate between different parts of your application, like a shared event bus.

• Real-Time Notifications: Create custom events to notify clients of updates or changes in real-time.

Complete Code Implementation:

const EventEmitter = require('events');
const myEmitter = new EventEmitter();

// Create a custom event
myEmitter.emit('custom-event', 'Hello, world!');

// Listen for the custom event
myEmitter.on('custom-event', (data) => {
  console.log(data); // Prints 'Hello, world!'
});

Potential Applications:

Custom events can be used in a wide range of applications, including:

• Logging and debugging

• Error handling

• Real-time communication

• Asynchronous task coordination

• Integration with other systems

---

Custom Logging

Custom Logging

What is Custom Logging?

Custom logging allows you to personalize the way nodemon logs messages to the console. You can change the format, color, and even add additional data to the log messages.

How to Use Custom Logging?

To use custom logging, you need to create a custom log formatter. A log formatter is a function that takes a log message and returns a formatted string.

Creating a Custom Log Formatter

Here is an example of a custom log formatter that adds a timestamp and color to the log messages:

const chalk = require('chalk');

const customFormatter = (level, msg, prefix) => {
  return `[${chalk.green(new Date().toISOString())}] ${chalk.blue(level)}: ${msg}`;
};

Using a Custom Log Formatter

Once you have created a custom log formatter, you can use it with nodemon by setting the --log-formatter option:

nodemon --log-formatter customFormatter.js

Real-World Applications of Custom Logging

• Adding additional data to log messages: You can add additional data to log messages, such as the current user or the request ID. This can help you track down issues more easily.

• Changing the format of log messages: You can change the format of log messages to make them more readable or to match your specific needs.

• Coloring log messages: You can color log messages to make them more visually appealing or to differentiate between different types of messages.

Here is a real-world example of how you can use custom logging:

const chalk = require('chalk');

const customFormatter = (level, msg, prefix) => {
  return `[${chalk.green(new Date().toISOString())}] ${chalk.blue(level)}: ${chalk.bold(prefix)} ${msg}`;
};

nodemon --log-formatter customFormatter.js

This custom log formatter will add a timestamp, color, and bold prefix to all log messages. This can make it easier to track down issues and to differentiate between different types of messages.

---

Versioning

Nodemon's Versioning

Semantic Versioning

Nodemon follows Semantic Versioning (SemVer), which uses a three-part version number format: MAJOR.MINOR.PATCH.

• MAJOR: Indicates significant changes that may break compatibility.

• MINOR: Indicates new features or improvements that don't break compatibility.

• PATCH: Indicates bug fixes or other minor updates.

Version Numbers

Each new release of Nodemon is assigned a version number based on the type of changes included:

• MAJOR Releases: 4.0.0, 5.0.0, etc. Indicate major architectural changes or breaking features.

• MINOR Releases: 3.2.0, 3.3.0, etc. Introduce new features or improve existing ones without breaking compatibility.

• PATCH Releases: 3.1.1, 3.1.2, etc. Fix bugs or make minor improvements without changing functionality.

Using Specific Versions

If you want to use a specific version of Nodemon, you can:

# Install a specific version globally
npm install -g nodemon@3.1.2

# Install a specific version in your project
npm install --save-dev nodemon@3.1.2

Updating Nodemon

To update Nodemon to the latest version:

# Update globally
npm update -g nodemon

# Update in your project
npm update --save-dev nodemon

Real-World Applications

Versioning helps:

• Maintain consistent behavior across different Nodemon versions.

• Allow for controlled upgrades and downgrades.

• Identify and solve bugs more efficiently.

---

Installation

Nodemon Installation

Overview

Nodemon is a tool that helps you automatically restart your Node.js application when you make changes to the code. This is useful for development, as it saves you from having to manually restart the application every time you make a change.

Installation

There are two ways to install Nodemon:

1. Global installation

This installs Nodemon globally, so you can use it from anywhere on your computer.

npm install -g nodemon

2. Local installation

This installs Nodemon locally, within the current project directory.

npm install nodemon --save-dev

Usage

Once Nodemon is installed, you can use it to run your Node.js application by passing the --watch flag.

nodemon --watch app.js

This will start your application and watch for changes to any files in the current directory. When a change is detected, Nodemon will automatically restart your application.

Real-World Applications

Nodemon is a useful tool for development, as it can save you time and effort. Here are some real-world applications for Nodemon:

• Web development: Nodemon can be used to automatically restart your web server when you make changes to the code. This means you can quickly see the changes you've made without having to manually restart the server.

• API development: Nodemon can be used to automatically restart your API when you make changes to the code. This means you can quickly test changes to your API without having to manually restart it.

• Command-line tool development: Nodemon can be used to automatically restart your command-line tool when you make changes to the code. This means you can quickly test changes to your tool without having to manually restart it.

---

Tutorials

Topic: What is Nodemon?

Simplified Explanation: Nodemon is a tool that helps you run and develop your Node.js applications more efficiently. It automatically detects changes in your code and restarts your application, so you don't have to do it manually.

Real World Application: When you're developing a Node.js application, you constantly make changes to your code. Nodemon saves you time by automatically restarting your application after each change, so you can quickly see the results of your modifications.

Example Code:

npm install -g nodemon

Topic: Auto-Reloading with Nodemon

Simplified Explanation: Auto-reloading means that Nodemon automatically restarts your application whenever it detects changes in your code files.

Real World Application: Auto-reloading is especially useful when you're debugging your code or testing different features. It allows you to make changes to your code quickly and see the results immediately.

Example Code:

nodemon app.js

Topic: Customizing Nodemon

Simplified Explanation: You can customize Nodemon's behavior to meet your specific needs. For example, you can specify which files to watch for changes, set a delay before restarting, or use a different script as the start command.

Real World Application: Customizing Nodemon can streamline your development workflow. You can tailor it to work with your specific project structure and preferences.

Example Code:

{
  "watch": ["src", "config"],
  "delay": "2000",
  "exec": "npm run start"
}

Topic: Watch Ignore

Simplified Explanation: Watch ignore allows you to exclude certain files or directories from being watched by Nodemon. This can improve performance and avoid unnecessary restarts.

Real World Application: Watch ignore is useful for excluding files that don't affect your application's behavior, such as test files or log files.

Example Code:

{
  "ignore": ["test", "logs"]
}

---

Case Studies

Case Studies

Introduction

Nodemon is a tool that helps you automatically restart your Node.js application when you make changes to the code. This can greatly improve your development workflow, as you no longer have to manually restart your application every time you make a change.

Case Study 1: Development Workflow

Problem: You are a developer who is constantly making changes to your Node.js application. Every time you make a change, you have to manually restart your application to see the results. This can be time-consuming and tedious.

Solution: You can use Nodemon to automatically restart your application when you make changes to the code. This will save you time and effort, and it will help you to be more productive.

Real-world example: You are working on a Node.js application that handles user registration. You want to make sure that the application is working properly, so you frequently test it by creating new user accounts. With Nodemon, you can automatically restart your application after each change, so you can quickly see if the changes have been applied correctly.

Code snippet:

// package.json
{
  "scripts": {
    "start": "nodemon src/index.js"
  }
}

Case Study 2: Deployment

Problem: You have deployed your Node.js application to a production server. However, you are concerned that if you make any changes to the code, you will have to manually restart the application on the server. This could cause downtime for your users.

Solution: You can use Nodemon to automatically restart your application on the server when you make changes to the code. This will ensure that your application is always running the latest version of the code, and it will minimize the risk of downtime.

Real-world example: You have deployed your Node.js application to a production server. You want to make sure that the application is always running the latest version of the code, so you install Nodemon on the server. Now, whenever you make changes to the code on your local machine, Nodemon will automatically restart the application on the server.

Code snippet:

// server.js
const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello, world!');
});

app.listen(3000, () => {
  console.log('Server listening on port 3000');
});

Case Study 3: Continuous Integration

Problem: You are using a continuous integration (CI) system to automatically build and test your Node.js application. However, the CI system does not automatically restart your application after each build. This can make it difficult to debug and test your application.

Solution: You can use Nodemon to automatically restart your application after each build. This will ensure that your application is always running the latest version of the code, and it will make it easier to debug and test your application.

Real-world example: You are using a CI system to automatically build and test your Node.js application. You want to make sure that the application is always running the latest version of the code, so you install Nodemon on your CI server. Now, whenever your CI system builds your application, Nodemon will automatically restart the application.

Code snippet:

// .gitlab-ci.yml
image: node:latest

stages:
  - build
  - test

build:
  stage: build
  script:
    - npm install
    - npm run build

test:
  stage: test
  script:
    - npm run test

Potential Applications

Nodemon can be used in a variety of real-world applications, including:

• Development workflow

• Deployment

• Continuous integration

• Debugging

• Testing

---

Ignoring Files

Ignoring Files in Nodemon

What is Nodemon?

Nodemon is a tool that automatically restarts a Node.js application when files change. This is useful during development to save you time from manually restarting the application whenever you make changes.

Ignoring Files

Nodemon can ignore certain files so that it doesn't restart the application when those files are modified. This is useful for files that don't affect the running application, such as logs or test files.

How to Ignore Files

You can ignore files in Nodemon by adding them to an ignore list. There are two ways to do this:

1. Command-line Option:

You can add files to the ignore list using the --ignore command-line option. For example:

nodemon --ignore "logs/*"

This will ignore all files in the logs directory.

2. Configuration File:

You can also specify ignored files in a configuration file named .nodemonignore. The configuration file should be placed in the same directory as your Node.js application. The following example ignores all files with a .log extension:

# .nodemonignore file

*.log

Real-World Application

Ignoring files in Nodemon can be helpful in the following situations:

• Logs: Ignore log files so that Nodemon doesn't restart the application when new log entries are created.

• Test files: Ignore test files so that Nodemon doesn't restart the application when you run tests.

• Node modules: Ignore Node modules so that Nodemon doesn't restart the application when you install or update modules.

• Large files: Ignore large files that take a long time to change, such as media files or archives.

Complete Code Implementation

The following example shows how to ignore all logs and test files in a Node.js application:

# .nodemonignore file

logs/*
test/*

# Run Nodemon
nodemon

This configuration will prevent Nodemon from restarting the application when any file in the logs or test directories is modified.

---

Error Codes

Error Code 1: Failed to fork:

• Meaning: The system couldn't create a new "worker" to run your app, like when you fork a process to create another copy of it. It's often caused by memory or resource issues.

• Example:

nodemon app.js

• Solution:

• Close any heavy apps or programs.

• Restart your computer.

• Update your Node.js version.

Error Code 2: Script exited with code 1:

• Meaning: The app you're running had an error that made it stop running. The error code 1 usually indicates a syntax error in your app's code.

• Example:

nodemon index.js

// index.js
console.log(sum(1, 2)); // sum is not defined

• Solution:

• Check your app's code for any errors.

• Check your app's dependencies to make sure they're installed and up-to-date.

Error Code 3: script exited without executing:

• Meaning: The app didn't actually start running. It could be caused by a problem with your app's "entry point," the file that it starts from.

• Example:

nodemon start.js

// start.js
require('./app.js'); // app.js is missing

• Solution:

• Check your app's entry point to make sure it exists and is being called correctly.

• Make sure that the app's dependencies are installed and up-to-date.

Error Code 4: exited with code null:

• Meaning: The app stopped running, but it didn't have an error code attached to it. This can be caused by a variety of reasons, like unexpected input or a crash.

• Example:

nodemon app.js

// app.js
process.stdin.on('data', (chunk) => {
  // Unexpected input crashes the process
  if (chunk === 'exit') {
    process.exit();
  }
});

• Solution:

• Check your app's code for any unexpected inputs or crashes.

• Check your app's dependencies to make sure they're installed and up-to-date.

---

Command Line Options

Command Line Options

--config, -c

• Specifies a path to a custom configuration file.

Example:

nodemon --config my-config.json

--delay, --watch-delay

• Sets the delay (in milliseconds) between file changes and when Nodemon restarts the application.

Example:

nodemon --delay 2000

--exec, -x, --exec-script, --exec-script-post

• Specifies a command to be executed when Nodemon starts, after each file change, or both.

Example:

nodemon --exec "echo 'Starting server...'" --exec-script "npm run lint"

--ext, --extensions

• Sets the file extensions to be watched by Nodemon.

Example:

nodemon --ext js,html

--ignore, -i, --ignore-pattern

• Specifies a glob pattern of files to be ignored by Nodemon.

Example:

nodemon --ignore node_modules

--inspect, -i

• Enables remote debugging of the Nodemon process.

Example:

nodemon --inspect

--no-debounce, --no-debounce-watch

• Disables the debounce delay (which groups file changes within the delay period before triggering a restart).

Example:

nodemon --no-debounce

--only, --only-files

• Restricts Nodemon to watching only the specified files or directories.

Example:

nodemon --only main.js,shared

--poll-interval, -p

• Sets the polling interval (in milliseconds) for checking file changes.

Example:

nodemon --poll-interval 250

--quiet, -q

• Suppresses output from Nodemon.

Example:

nodemon --quiet

--require, -r

• Adds a module to the Nodemon process before any application code is executed.

Example:

nodemon --require ./my-logger.js

--script, -s

• Specifies the path to the entry point script for the application.

Example:

nodemon --script my-app.js

--signal, --signal-delay, --signal-watch

• Configures how signals (such as SIGINT and SIGTERM) are handled by Nodemon.

Example:

nodemon --signal SIGUSR2 --signal-delay 1000

--trace, -t

• Outputs debug information to the console.

Example:

nodemon --trace

--verbose, -v

• Increases the verbosity of Nodemon's output.

Example:

nodemon --verbose

--watch, -w, --watch-dirs, --watch-extensions, --watch-ignore

• Configures the directories, file extensions, and ignored files/directories to be monitored by Nodemon.

Example:

nodemon --watch src --watch-extensions js,json --watch-ignore node_modules

Real-World Applications

• --config: Allows for customization of Nodemon's behavior through a dedicated configuration file.

• --delay: Prevents excessive restarts when files change rapidly (e.g., during development with live-reload).

• --exec: Executes commands before/after Nodemon restarts, such as running tests or database migrations.

• --ignore: Excludes specific files or directories from monitoring to avoid unnecessary restarts.

• --inspect: Enables remote debugging of Nodemon for troubleshooting issues.

• --no-debounce: Reduces restart latency by processing file changes immediately without delay.

• --only: Focuses monitoring on specific files or directories, improving performance in large codebases.

• --poll-interval: Adjusts the file change detection frequency, allowing for conservative monitoring in production environments.

• --require: Loads required modules before executing application code, enabling pre-configuration or utility initialization.

• --script: Specifies the entry point for the application, ensuring that Nodemon monitors the correct script.

• --signal: Configures how Nodemon handles signals, allowing for graceful application shutdown or logging.

• --trace: Outputs detailed debugging information, aiding in problem resolution.

• --verbose: Provides additional output for monitoring Nodemon's activities and identifying potential issues.

• --watch: Customizes the monitoring behavior, allowing for targeted file change detection in specific directories or with specific extensions.

---

Monitoring Changes

Monitoring Changes with Nodemon

What is Nodemon?

Nodemon is a tool that watches for changes in your code and automatically restarts your Node.js application when you make updates. This is useful for development, as it saves you from having to manually restart your app every time you make a change.

How to Use Nodemon

To use Nodemon, install it globally with npm:

npm install -g nodemon

Then, simply run your Node.js script with Nodemon:

nodemon script.js

Monitoring Changes

Nodemon monitors changes in the following directories:

• The current directory

• Any subdirectories that contain Node.js files

• Any symbolic links to Node.js files

When Nodemon Detects Changes

When Nodemon detects changes in any of these directories, it will:

1. Gracefully restart your application.

2. Log a message to the console indicating that it has restarted your app.

Code Snippet

// script.js
console.log('Hello, world!');

// Run with Nodemon
nodemon script.js

Real-World Applications

Nodemon is useful in the following scenarios:

• Development: Nodemon allows you to quickly iterate on your code without having to manually restart your app.

• Testing: Nodemon can be used to automatically restart your test suite when you make changes to your code.

• Deployment: Nodemon can be used to monitor changes in production and automatically update your application.

---

Introduction

Introduction to Nodemon

What is Nodemon?

Nodemon is a tool that automatically restarts your Node.js application whenever you make changes to your code. This is very useful for quickly developing and testing applications, as you don't need to manually restart the application every time you change something.

How does Nodemon work?

Nodemon uses a file watcher to monitor your code for changes. When Nodemon detects a change, it automatically restarts the application. This is done without losing any state or data in your application.

Installing Nodemon

To install Nodemon, run the following command in your terminal:

npm install -g nodemon

Using Nodemon

To use Nodemon, simply run the following command in your terminal:

nodemon my-app.js

This will start Nodemon and watch your application for changes. When you make a change, Nodemon will automatically restart the application.

Benefits of using Nodemon

• Faster development: You don't need to manually restart your application every time you change something.

• Easier testing: You can quickly test different changes to your code without having to restart the application each time.

• Improved productivity: Nodemon can help you be more productive by automating the task of restarting your application.

Real-world examples

Here is a real-world example of how Nodemon can be used:

• A developer is working on a new Node.js application. The developer is constantly making changes to the code and wants to see how the changes affect the application's behavior. With Nodemon, the developer can simply make the changes and Nodemon will automatically restart the application. This saves the developer time and hassle.

• A testing team is testing a new Node.js application. The testing team is running multiple tests on the application and wants to see how the application behaves under different conditions. With Nodemon, the testing team can simply make changes to the application's code and Nodemon will automatically restart the application. This saves the testing team time and effort.

Potential applications

Nodemon can be used in any situation where you need to automatically restart a Node.js application when you make changes to the code. Some potential applications include:

• Development

• Testing

• Deployment

• Continuous integration

---

Delaying Restart

Delaying Restart Topic

Imagine you have a running application that you're working on, and you're making changes to the code. Nodemon is a tool that automatically restarts your application when you make changes, which is convenient, but sometimes you may want to delay the restart for a while.

1. delay Option

The delay option specifies how long Nodemon should wait after detecting changes before restarting your application. This can be useful if you're making multiple changes in a short amount of time and you don't want Nodemon to restart multiple times unnecessarily.

Code Snippet:

{
  "delay": 500 // Wait 500 milliseconds before restarting
}

2. legacyWatch: true

Setting legacyWatch: true tells Nodemon to use its legacy file watching mechanism, which delays restarts until all files have been saved. This can be helpful if you have a large project with many files, and you want to make sure that Nodemon only restarts when all the changes have been made.

Code Snippet:

{
  "legacyWatch": true
}

3. ignoreChanges and ignore Options

The ignoreChanges and ignore options allow you to specify certain files or directories that Nodemon should ignore when watching for changes. This can be useful if you have files that are constantly being updated (such as logs) and you don't want Nodemon to restart every time they change.

Code Snippet:

{
  "ignoreChanges": ["logs/**/*"],
  "ignore": ["node_modules/**/*"]
}

Real-World Applications

• Delaying restarts to reduce unnecessary server downtime: By setting an appropriate delay, you can prevent Nodemon from restarting multiple times if you're making frequent changes.

• Handling large projects efficiently: By using the legacyWatch option, you can ensure that Nodemon only restarts when all changes have been saved, even in large projects with many files.

• Ignoring unnecessary files: By using the ignoreChanges and ignore options, you can prevent Nodemon from restarting when files that don't affect the application's behavior are updated.

---

Monitoring Multiple Directories

Monitoring Multiple Directories with Nodemon

Explanation

Nodemon is a tool that can monitor files and folders for changes and automatically restart your Node.js application when a change is detected. This is useful for development, as it eliminates the need to manually restart your application every time you make a change to your code.

By default, Nodemon only monitors the current directory. However, you can also specify additional directories to monitor. This can be useful if you have multiple directories associated with your project, such as a source directory and a test directory.

Code Snippets

The following code snippet shows how to specify additional directories to monitor:

const nodemon = require('nodemon');

nodemon({
  watch: ['src', 'test'], // array of directories to monitor
});

Real World Complete Code Implementation and Examples

The following is a complete example of how to use Nodemon to monitor multiple directories:

# Create a new Node.js project
mkdir my-project
cd my-project

# Initialize a new npm project
npm init -y

# Install Nodemon
npm install --save-dev nodemon

# Create a src directory
mkdir src

# Create a source file in the src directory
touch src/index.js

# Create a test directory
mkdir test

# Create a test file in the test directory
touch test/test.js

# Create a package.json file
echo '{
  "name": "my-project",
  "version": "1.0.0",
  "devDependencies": {
    "nodemon": "^2.0.0"
  },
  "scripts": {
    "start": "nodemon --watch src --watch test"
  }
}' > package.json

# Start Nodemon
npm start

This example will start Nodemon and monitor the src and test directories for changes. If any changes are detected, Nodemon will automatically restart your Node.js application.

Potential Applications in Real World

Monitoring multiple directories with Nodemon can be useful in the following scenarios:

• Monitoring a source directory and a test directory to ensure that tests are run automatically when changes are made to the source code.

• Monitoring a configuration directory to automatically reload configuration files when they are changed.

• Monitoring a log directory to automatically display new log entries as they are created.

---

Error Output

Nodemon Error Output

What is Nodemon?

Nodemon is a tool that helps you develop Node.js applications by monitoring and automatically restarting your code whenever you make changes to it.

Error Output

When Nodemon encounters an error, it will display an error message in its output. These messages can be helpful in identifying and resolving issues with your code.

Error Types

Nodemon can display various types of errors, including:

• Syntax errors: These errors occur when there is a syntax issue in your code, such as a missing semicolon or an incorrect operator.

• Runtime errors: These errors occur while your code is running, such as a reference to a non-existent variable or a logic error.

• Configuration errors: These errors occur when there is a problem with your Nodemon configuration, such as an invalid script path or an unsupported option.

Error Messages

The error message displayed by Nodemon typically provides information about the type of error and its location in your code. Here are examples of some common error messages:

• SyntaxError: Unexpected token - This error indicates a syntax issue in your code.

• TypeError: Cannot read properties of undefined (reading 'x') - This error indicates that you are attempting to access a property of an undefined variable.

• ConfigError: Script path does not exist - This error indicates that the script path specified in your Nodemon configuration does not exist.

Error Output Format

Nodemon's error output typically follows a standard format:

[Error] <error message>
<file path>:<line number>:<column number>

For example:

[Error] SyntaxError: Unexpected token
src/main.js:10:5

This error message indicates a syntax error in the file src/main.js, on line 10, column 5.

Real-World Applications

Nodemon's error output can be used in various real-world applications, such as:

• Debugging applications: The error output can help you identify and resolve issues with your code during the development process.

• Monitoring applications: You can use Nodemon's error output to monitor your applications in production and receive alerts whenever an error occurs.

• Logging errors: You can configure Nodemon to log error messages to a file or database for future reference.

---

Error Handling Strategies

Error Handling Strategies

1. Exit on Error (Default)

• Nodemon will immediately exit the process when an error occurs.

• Example:

nodemon app.js

If app.js has an error, Nodemon will print the error message and exit.

2. Reload on Error

• Nodemon will automatically restart the process if an error occurs.

• Example:

nodemon -r app.js

If app.js has an error, Nodemon will print the error message and restart the process.

3. Ignore Errors

• Nodemon will continue running even if an error occurs.

• Example:

nodemon --ignore-errors app.js

If app.js has an error, Nodemon will print the error message but continue running.

4. Custom Error Handler

• You can define a custom error handler function to handle errors as you want.

• Example:

nodemon --exec '/bin/sh -c "echo Error occurred"; exit 1"' app.js

This will print "Error occurred" and exit the process with exit code 1.

Real-World Applications:

• Auto-reloading: Reloading on error is useful for development when you want to automatically see changes after making code changes.

• Error logging: Ignoring errors can be useful for production environments where you don't want the process to crash, but you want to log the errors for debugging.

• Custom error handling: Custom error handlers allow you to handle errors in a specific way, such as sending an email notification or triggering a backup process.

---

Best Practices

Best Practices for Using Nodemon

1. Use a Nodemon Config File

A Nodemon config file allows you to customize Nodemon's behavior. To create a config file, create a .nodemonrc or .nodemonrc.json file in your project directory.

Example:

{
  "watch": ["server.js", "routes/*.js"],
  "ignore": ["node_modules/"],
  "ext": "js,json"
}

2. Configure Restart Rules

Nodemon can restart your application based on specific file changes. You can configure these rules using the watch, ignore, and ext options in the config file.

Example:

{
  "watch": ["server.js", "routes/*.js"],
  "ignore": ["node_modules/"],
  "ext": "js,json"
}

In this example, Nodemon will only restart the application when changes are made to .js or .json files in the server.js and routes directories.

3. Use Multi-Process Mode

Multi-process mode allows Nodemon to run your application in multiple child processes. This can improve performance and reduce restart times.

Example:

{
  "execMap": {
    "js": "node --inspect-brk=9229"
  }
}

In this example, Nodemon will run the application in a child process with the --inspect-brk=9229 flag.

4. Enable Debugging

You can enable debugging using the --inspect-brk flag. This will launch a debugger and allow you to inspect the state of your application while it's running.

Example:

{
  "execMap": {
    "js": "node --inspect-brk"
  }
}

5. Use a Custom Bin Folder

You can use a custom bin folder to store your Nodemon executable. This is useful if you want to use a specific version of Nodemon that's not installed globally.

Example:

$ mkdir ~/.nodemon-bin
$ npm install nodemon@latest -g --bin-folder=~/.nodemon-bin
$ ln -s ~/.nodemon-bin/nodemon /usr/local/bin/nodemon

Real-World Applications

Nodemon is a useful tool for development because it allows you to:

• Quickly restart your application when you make changes to your code.

• Configure restart rules to only restart your application when specific files are changed.

• Use multi-process mode to improve performance and reduce restart times.

• Enable debugging to inspect the state of your application while it's running.

---

FAQs

FAQ 1: What is Nodemon and What Does it Do?

Simplified Explanation: Nodemon is like a watchful babysitter for your Node.js code. It keeps an eye on your code and whenever you make changes, it automatically restarts your Node.js application. This saves you the hassle of manually stopping and starting your application every time you make a change.

Example: nodemon index.js

This command starts your application (index.js) with Nodemon monitoring it. If you make changes to index.js, Nodemon will automatically restart the application for you.

Applications in Real World:

• Continuous testing during development

• Quick iteration when debugging code

FAQ 2: How Do I Ignore Specific Files or Directories from Nodemon?

Simplified Explanation: You can tell Nodemon to ignore certain files or directories so it doesn't restart your application when they change. This is useful for files like .env or node_modules, which don't typically require a restart.

Example:

nodemon --ignore '.env' --ignore 'node_modules' index.js

This command starts your application, ignoring changes to .env and node_modules.

Applications in Real World:

• Ignoring sensitive files like .env that should not trigger restarts

• Excluding vendor dependencies (e.g., node_modules) from restart considerations

FAQ 3: How Do I Set Nodemon to Watch for Changes in a Specific File or Directory?

Simplified Explanation: You can specify which files or directories Nodemon should watch for changes. This is helpful if you want to monitor specific parts of your code for changes.

Example:

nodemon --watch 'app.js' --watch 'routes' index.js

This command starts your application and only monitors changes to app.js, routes directory, and index.js.

Applications in Real World:

• Monitoring only relevant files during development

• Watching for specific file changes for testing and debugging

FAQ 4: How Can I Customize the Output of Nodemon?

Simplified Explanation: You can adjust how Nodemon displays output to your terminal. This allows you to customize the level of detail and verbosity of the logs.

Example:

nodemon --quiet --verbose index.js

This command starts your application, suppressing normal output (--quiet) but showing detailed logs (--verbose).

Applications in Real World:

• Tailoring output to your specific needs

• Increasing debugging information when necessary

FAQ 5: Troubleshooting: Why is Nodemon Not Reloading My Code?

Simplified Explanation: If you're having issues with Nodemon not reloading your code, check the following:

• Make sure Nodemon is installed and up-to-date.

• Ensure you're running Nodemon with the correct command (e.g., nodemon index.js).

• Verify that your code changes are being saved correctly.

• Check if your Node.js version and the Nodemon version are compatible.

Applications in Real World:

• Debugging common issues with Nodemon during development

---

Extending Nodemon

Extending Nodemon

Nodemon is a popular tool for monitoring changes in Node.js applications and automatically restarting the application when changes are detected. It's highly customizable, and you can extend its functionality to suit your specific needs.

Event Hooks:

Nodemon emits events at different stages of its lifecycle. You can listen to these events and execute custom code. For example:

nodemon.on('start', () => {
  console.log("Application started");
});

nodemon.on('change', (files) => {
  console.log(`Files changed: ${files}`);
});

File Watcher:

Nodemon uses an underlying file watcher to detect file changes. You can customize the file watching behavior by implementing your own file watcher and passing it to Nodemon:

// Custom file watcher using chokidar
const chokidar = require('chokidar');
const customFileWatcher = chokidar.watch('path/to/watch', {
  ignoreInitial: true,
  persistent: true,
});

nodemon({
  watch: customFileWatcher,
});

CLI Options:

Nodemon's CLI offers flexible control over its behavior. You can extend it by adding custom CLI options:

// Custom CLI option for specifying a custom port
const customCliOption = {
  name: 'my-port',
  description: 'Custom port to run the server on',
  type: 'number',
  default: 8080,
};

nodemon.cli.options.push(customCliOption);

Task Runner:

Nodemon can be used to run custom tasks before or after starting or restarting your application. You can create your own tasks by implementing the taskRunner method:

class CustomTaskRunner {
  execute(command, options) {
    // Custom task execution
    console.log(`Executing custom task: ${command}`);
  }
}

nodemon({
  taskRunner: new CustomTaskRunner(),
});

Applications:

• Custom file watching: For applications that require specific file watching behavior, such as ignoring certain files or folders.

• Enhanced CLI control: To provide advanced configuration options or automation through CLI commands.

• Custom task automation: To automate pre- or post-processing tasks, such as database migrations or code linting.