Difference between npm and npx commands

Npm is the default package manager for the JavaScript runtime environment Node.js. It is used to install and manage packages (libraries, frameworks, utilities, etc.) that are published on the npm registry, as well as to manage dependencies and to run scripts defined in a project's package.json file.

Here are some examples of how npm can be used:

• To install a package and add it to your project’s dependencies:

$ npm install react --save

This will install the react package and add it to the dependencies section in your package.json file. The --save flag indicates that the package should be added to the dependencies section, so that it will be installed when running npm install in the future.

• To install a package and add it to your project’s devDependencies:

$ npm install jest --save-dev

This will install the jest package and add it to the devDependencies section in your package.json file. The --save-dev flag indicates that the package should be added to the devDependencies section, which is used for development-only packages such as testing frameworks.

• To install a package globally:

$ npm install -g create-react-app

This will install the create-react-app package globally on your system, allowing you to use it from any directory. The -g flag indicates that the package should be installed globally.

• To run a script defined in a package’s package.json file:

$ npm run test

This will run the test script defined in your package.json file. This might be used to run tests for your project, for example.

NPX is a tool that is also included with npm. It allows you to run Node.js packages that are installed locally or globally in your project, without the need to install them globally on your system. This can be useful if you want to use a package temporarily for a one-off command, or if you want to ensure that you are using the correct version of a package that is specified in your project's package.json file.

Here are some examples of how npx can be used:

• To run a package’s command-line interface:

$ npx create-react-app my-app

This will create a new React app in the my-app directory, using the create-react-app package. You don't need to have create-react-app installed globally on your system in order to use it.

• To run a script defined in a package’s package.json file:

$ npx react-scripts test

This will run the test script defined in the react-scripts package, which is typically used to run tests for a React app.

• To run a package that is not installed in your project:

$ npx cowsay "Hello, world!"

This will run the cowsay package, which displays a message in a cow-like ASCII art. The package will be downloaded and run temporarily, without the need to install it globally or locally in your project.