My Node.js learning path (2) NPM module management_node.js

NPM is a Node package management and distribution tool that has become an unofficial standard for publishing Node modules (packages). With NPM, you can quickly find the packages used by specific services, download, install and manage installed packages.

Commonly used commands in NPM include:

（1）$ npm install moduleNames
Install Node module
Note: If you don’t know the name of the module when using it, you can follow the Find the desired module using the index value. npm also provides the query function $ npm search indexName After the installation is completed, a node_modules directory will be generated, under which are the installed node modules.
The installation of node is divided into global mode and local mode. Normally it will run in local mode and the package will be installed
Go to the local node_modules directory that contains statistics about your application code. In global mode, the Node package will be
Install it into node_modules in the Node installation directory. The global installation command is
                                                                                                                 Learn to use $npm set global=true to set the installation mode
                        , $npm get global can view the currently used installation mode.


（2）$ npm view moduleNames

View the package.json folder of the node module

Note: If you want to view the content of a tag under the package.json folder, you can use
                                                                      

（3）$ npm list
View the installed node packages in the current directory

Note: Node module search starts from the current directory where the code is executed, and the search results depend on the currently used directory

Contents under node_modules. $ npm list parseable=true can display the current content in the form of a directory
All node packages installed before


（4）$ npm help
View help command

（5）$ npm view moudleName dependencies
View package dependencies

(6)$ npm view moduleName repository.url
View the source file address of the package

（7）$ npm view moduleName engines
View the version of Node that the package depends on

（8）$npm help folders
View all folders used by npm

（9）$ npm rebuild moduleName
                                                                                                                                       Used to rebuild after changing the package content

（10）$ npm outdated
Check whether the package is outdated, this command will list all outdated packages, and you can update the package in time

（11）$ npm update moduleName
Update node module

（12）$ npm uninstall moudleName
Uninstall node module

(13) An npm package is a folder containing package.json, and package.json describes the structure of this folder. Visit
The method to ask npm for the json folder is as follows:
                                                            This command will open a webpage in the default way. If the default opening program is changed, it may not open as a webpage
open.

(14) When publishing an npm package, you need to check whether a certain package name already exists

                                  $ npm search packageName

(15) Many times when we use an npm package, we often forget to require its interdependent modules. We can

Use the following command to check the interdependent packages of this module

npm is the package manager for Node.JS. When doing Node.JS development, it is often used to install/uninstall packages. In fact, it does the work of publishing packages.

Configuration package.json

To package a program, you must first configure various settings, which are specified by package.json in the root directory of the package. The content of package.json must be in strict JSON format, that is:

Strings must be enclosed in double quotes, not single quotes;

The attribute name must be enclosed in double quotes;
Never add an extra comma after the last attribute.
There are many attributes of the configuration object. For details, please refer to here. Here are the commonly used items:

name: package name, which cannot be the same as an existing package.

version: version number.
description: A short introduction.
author: author information. Contains three attributes: name, email, and url.
bin: If there is an executable file in the program (mainly called from the command line), specify it here. You can specify multiple files.
main: The program entry when calling this package using require.
dependencies: Dependent packages, version numbers can be specified.

After configuring package.json, you can package and install it locally first to test whether the program operates normally. The installation command is:

npm install

In addition, there is an unspoken rule to pay attention to. If you want the executable program in the package to run in the Node.JS environment, then please add this line at the front of the program entry file:

#!/usr/bin/env node

Without this line, it will open in the system default mode instead of running in the Node.JS environment.

Register npm account

To publish the package to npm, you need to register an account first. npm does not provide a web version of the registration wizard. Registration also needs to be done through the command line:

npm adduser

After executing this command, prompts for entering your username, email, and password will appear in sequence. Just wait for a while after entering them.

Publish package

The preparations are all done. Execute the following command to publish the package:

npm publish
If you want to update the package, just modify the version number in package.json and re-execute the publish command.