SoFunction
Updated on 2025-04-12

Specific use of Nodemon tools

NodemonIt is a very practical development tool in the ecosystem, used to monitor file changes and automatically restart the server, thereby improving development efficiency. Especially during the back-end development process, frequent code modification and server restart operations are extremely cumbersome, andNodemonBy automating these processes, developers can focus on the code itself. This article will introduce in detailNodemonBasic usage methods, configuration options and their application scenarios in actual development.

1. Introduction to Nodemon

1. What is Nodemon?

Nodemonis a development tool built on the basis of   , designed to help developers automatically monitor changes in project files. Whenever a file changes,NodemonThe server will be automatically restarted without manually stopping and restarting. This is very helpful for improving development speed and reducing manual operations, especially when building back-end services or API interfaces.

2. How Nodemon works

NodemonThe core working principle is to listen for file changes in the project directory. Specifically,NodemonWill listen for files of the specified type (such as.js、.jsonChanges to the file and automatically execute the specified startup command when a change is detected (usuallynode ). It supports customizing listening rules and ignoring specific directories or files through command line parameters or configuration files.

2. Nodemon installation and basic use

1. Install Nodemon

InstallNodemonVery simple, just need to do a global or local installation via npm or yarn. The following are two installation methods:

# Global installationnpm install -g nodemon

# Or use yarnyarn global add nodemon

# Local installation of the projectnpm install --save-dev nodemon

After global installation, you can use it directly in any projectnodemonOrder. Local installation is suitable forNodemonAs a project's development dependency,Configure the startup script.

2. Basic use

After the installation is completed,NodemonThe use is very simple. Just run the following command in the project directory.NodemonYour application will be automatically started and the file changes will begin to be monitored:

nodemon

In this example,NodemonWill startAnd automatically monitor the changes in the file. Once the code changes, the server will automatically restart.

You can also passnpxDirectly run local installationNodemon：

npx nodemon

3. Configure in

To simplify command line operations, you canNodemonThe command to configureFiledscriptsIn part, this waynpm runYou can start the project:

{
  "scripts": {
    "start": "nodemon "
  }
}

Then, just run the following command:

npm start

3. Advanced configuration of Nodemon

NodemonNot only can it simply monitor file changes, it also provides rich configuration options that allow developers to customize behavior according to their needs.

1. Configure through command line parameters

NodemonSupports multiple command line parameters to customize their behavior, common options include:

  • -e: Specify the type of file to listen on. For example, listen only.jsand.htmldocument:
nodemon -e js,html
  • --ignore: Ignore specific files or directories to avoid unnecessary restarts. For example, ignorenode_modulesTable of contents:
nodemon --ignore node_modules/
  • -w: Explicitly specify the directory to listen for. For example, monitorsrcFile changes in the directory:
nodemon -w src

2. Customize through configuration files

In addition to command line parameters, you can also use the configuration file () to saveNodemonConfiguration information. This file is usually located in the root directory of the project, and the configuration options are similar to command line parameters. For example, the following is a common oneConfiguration file:

{
  "watch": ["src"],
  "ext": "js,json",
  "ignore": ["node_modules", "test"],
  "exec": "node "
}

In this configuration file, we set up listeningsrc In the directory .jsand.jsonFiles, and ignore them at the same timenode_modulesandtestTable of contents.

3. Automatic restart delay

In some cases, excessive file storage frequency may causeNodemonFrequently restarted. At this time, you can control the restart frequency by setting the delay. For example, the following command sets a 2-second restart delay:

nodemon --delay 2

4. Application scenarios in actual development

1. Applications in API development

During API development, server code needs to be adjusted frequently, such as modifying routes, controller logic, etc. If you need to manually restart the server after each modification, it is not only inefficient, but also easy to miss certain restart steps. By usingNodemon, developers can focus on business logic without caring about server startup and restart issues.

nodemon

2. Front and back end joint debugging

In some projects with the separation of front-end and back-end, back-end services may need to be coordinated with the front-end. When the current side modify the request parameters or the back end adjusts the response structure, the server needs to be restarted.NodemonIn this case, the backend service can be automatically restarted to reduce the hassle of manual operations by developers and improve development efficiency.

3. Improve efficiency of local development environment

For large projects, in local development environments, the code volume is large and the modules are complex, and manually restarting the server will significantly reduce development efficiency.NodemonIt can automatically manage restart logic by monitoring changes in multiple modules to improve the development experience.

5. Nodemon's FAQs and solutions

1. Nodemon cannot listen for file changes

sometimes,NodemonThe file changes cannot be detected, which may be caused by file system restrictions or listening to too many files. It can be reduced by reducing the number of files to listen to or usinglegacyMode to solve:

nodemon --legacy-watch

2. Nodemon high CPU usage issues

In big projects,NodemonIt may take up high CPU resources because it requires monitoring a large number of files. To solve this problem, it can be optimized by:

  • use--ignoreIgnore unnecessary directories (such asnode_modules）。
  • Restrict the type of file to listen, such as listening only.jsdocument.
  • useConfiguration files to fine-grained control of the listening range.

6. Summary

NodemonIt is an indispensable tool in development, which can significantly improve development efficiency and reduce the cumbersome operation of manually restarting the server. Through reasonable useNodemonConfiguration options, developers can customize monitoring rules according to project needs and optimize local development processes. Whether in API development, front-end joint debugging, or in large-scale projects,NodemonAll can provide convenience for developers, making the development process smoother and more efficient.

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