Node package depends on download management

Search the folder cmd Press enter to call up node Command prompt

Check for installation   Input node -v

The version number appears v16.... Description installation successful

Create a json package , Input npm init

The fastest way is to enter npm init -y Enter to Is this OK?

Download the latest js Packet dependency , Input npm install jquery, Download the reference installation package , Finally, the packaged files are dist In the folder

There are three ways to download the version , It can solve the problems encountered in work

The first one is :npm install Download package depends on

Notice that we npm install( Abbreviation :npm i) When the installation package depends ,^ The up arrow will automatically upgrade the small version , Will be able to 3.5.0 Upgrade package dependency to 3.6.0, As a result, it is not supported in the project

resolvent : Install the version you want , Then don't add ^ up arrow , Because of the addition of ^ up arrow , Will automatically help you upgrade to the latest version . Remember that !!!

The second kind :npm i [email protected] Version number

Then download it jquery Appoint Version number of , You can input npm i [email protected] Version number , You can download the version number

The third kind of :npm i [email protected]

There is another case where you don't know the specific sub version you want to download , Only know the main version , You can input npm i [email protected] Download the latest content of the latest large version

Get to know jquery How are the version numbers of

Illustrate with examples : v3.6.0

3: Represents the main version There are big differences between large versions , Generally, it is a major update

6: Represents the next version Compatible with new features

0: Represents revision number Compatibility correction

Two environments for development

The first one is : The production environment is used for the official launch of the project   Enter the command  

example :npm i [email protected] or  npm i bootstrap --save  or npm i vue -S

The second kind : You can enter commands for the dependencies needed by the development environment

packages.json The following content will appear in , Representing the development environment requires package dependencies

example :npm i moment --save-dev  or  npm i vue -D  or  npm i moment -D

Environmental reasons :

Finally, we need to package the project , To improve performance , Generally, only the development environment is packaged , Save performance , And if the production environment has been downloaded , Note that the development environment is downloaded at this time , The dependent packages in the production environment will disappear , There is only a development environment , But it does not affect our use .

Uninstall dependency package :

Input :npm uninstall jquery( Abbreviation :npm unijquery)