NPM command -- install dependent packages -- Usage / explanation

Original website ：npm command -- Install dependency packages -- usage / Detailed explanation _IT A blog with a sharp blade -CSDN Blog

brief introduction

        In this paper, npm How to install dependent packages .

usage

command	effect	detailed
npm install <pkg>      // A synonym for ：i, isntall, add	install pkg package	To download pkg, Then download pkg Of packages.json Inside dependencies、devDependencies Dependencies of, etc .         If there is... In the path where the command is executed packages.json, Then add this dependency to its dependencies.
npm install pkg1 pkg2	Install multiple packages
npm install git://github.com/package/path.git	from git Download and install
npm install [email protected] npm install [email protected] npm install [email protected]">=0.1.0 <0.2.0"	Specified version number	Install the latest version by default , If you want to install a specific version of the module , You can add... After the module name @  And version number .

Parameters

Parameters	explain	detailed
-f/--force	Mandatory installation . Reinstall whether it has been installed or not .	Before the installation ,npm install Will check node_modules Whether the specified module already exists in the directory . If there is , It's not going to be reinstalled , Even if there is a new version of the remote repository , So it is with .
-g/--global	Global installation	Please see below ：“ Local installation / Global installation ”
-P/--save-prod -S/--save（ The old version ）	Add the module name to the production phase dependency ： dependencies	Add module name to packages.json Of documents dependencies term . If there is... In the path where the command is executed packages.json, Not specifying this parameter will also add this dependency to its dependencies.
-D/--save-dev	Add the module name to the development phase dependency ：devDependencies	Add module name to packages.json Of documents devDependencies term .
-O|--save-optional	Add module name to optionalDependencies	Add module name to packages.json Of documents optionalDependencies term . // I don't know the function of this at present
-E/--save-exact	Precisely install the specified version of the module	With this option dependencies Field in front of each module version number ^ Be missing .
--dry-run	Just run the command , It's not actually installed

Local installation / Global installation

If you want to have local installation and global installation , You need to install it or use it in two places npm link.

Local installation

command

npm install <Module Name>

Detailed explanation

1. Will put the installation package in ./node_modules Next （ function npm The directory where the command is located ）, without node_modules Catalog , Will be executed in the current npm Command directory to generate node_modules Catalog .
2. Can pass require() To introduce locally installed packages .

Global installation

command

npm install <package> -g

Detailed explanation

1. It is placed in the user directory by default . Can pass npm get prefix Check the installation location
   Default location linux: /usr/local windows: C:\Users\xxx\AppData\Roaming\npm
2. It can be used directly in the command line .

The method of installing to the specified location during global installation

Law 1： Modify the configuration

     establish node_cache And node_global Folder , Then set the Global installation location

npm set cache D:\ST\nodejs\node_cache
npm set prefix D:\ST\nodejs\node_global

Law 2： Specify the location during installation

npm install --prefix ./install/here <package>