53. What are devDependencies and dependencies in package.json?

In the package.json file, dependencies and devDependencies are sections that define the external libraries required by the project.

dependencies:

• Description: These are packages required to run the application in a production environment. They typically include libraries that are essential for the application to function, such as express for a server application.
• How to add:

npm install <package-name> --save

• Example in package.json:

"dependencies": {
  "express": "^4.17.1"
}

devDependencies:

• Description: These are packages required only during the development of the project and are not needed in a production environment. They include testing, compiling, building tools, and other development utilities like jest or webpack.
• How to add:

npm install <package-name> --save-dev

• Example in package.json:

"devDependencies": {
  "jest": "^26.6.3",
  "webpack": "^5.24.4"
}

Differences:

• dependencies: Installed when the project is deployed on a production server.
• devDependencies: Installed only in a development environment.

The distinction between dependencies and devDependencies allows for efficient dependency management, ensuring that only necessary packages are deployed to the production environment.