Commonly Used npm Flags

Commonly Used npm Flags

-g (global)

• Cmd: npm install -g <package-name>
• Usage: Installs the package globally on your system, making it available from any directory. This is useful for tools and utilities you want to use across different projects.
• Example: npm install -g create-react-app allows you to use the create-react-app command from anywhere on your machine.

-p (prefix)

• Cmd: npm install -p <directory> <package-name> 
• Usage: Installs the package to a specific directory rather than the default node_modules in the current project. This can be used to manage packages for different environments or users.
• Example: npm install -p /usr/local <package-name> installs the package to /usr/local.

-d (save-dev)

• Cmd: npm install -D <package-name> or npm install --save-dev <package-name> 
• Usage: Adds the package as a development dependency. Development dependencies are only needed during development and testing, not in production. 
• Example: npm install -D jest adds jest to your devDependencies in package.json

{
  "dependencies": {
    "express": "^4.17.1"
  },
  "devDependencies": {
    "jest": "^27.0.6"
  }
}

Other Common npm Flags

--save(-S)

• Cmd: npm install -S <package-name> or npm install <package-name> 
• Usage: Adds the package as a dependency in your package.json. This is the default behavior when you run npm install <package-name> 
• Example: npm install express will add express to the dependencies in package.json 

--save-optional (-O)

• Cmd: npm install -O <package-name>
• Usage: Adds the package as an optional dependency. These dependencies are not critical for the project to function but can add optional features.
• Example: npm install -O fsevents adds fsevents to optionalDependencies.

--save-exact (-E)

• Cmd: npm install -E <package-name> 
• Usage: Installs the exact version specified without updating to newer versions.
• Example: npm install -E lodash installs the exact version listed, e.g., lodash@4.17.21

--production

• Cmd: npm install --production
• Usage: Installs only the dependencies listed under dependencies and skips devDependencies. Useful for deployment.
• Example: npm install --production ensures only necessary packages for running the app are installed.

Summary

• -g: Global installation
• -p: Specify installation directory
• -d: Development dependencies
• --save: Default dependency installation (often implicit)
• -O: Optional dependencies
• -E: Exact version installation
• --production: Production-only installation

These flags help configure your environment and dependencies according to your project needs.

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