NPM is a registry, command line interface, and a website. The registry is where ‘packages’ is hosted so that people can download it. The command line interface (CLI) is the program we use to interact with the registry. The website is where we search for a package and where we can do administration task regarding the package we hosted on registry.

Package

A package is a folder with package.json file inside it. This file will contains the information of the package such us the name, version, and the main file. Main file is the file used when someone is importing your code using require keyword in javascript.

Publishing a package

To publish a package, you must ensure that you are logged in using CLI:

npm login

Then, once the package is complete. You can publish using:

npm publish

Installing a package

You can install a package to your project in two ways.

Installing a package using CLI

When you build the software, most likely you will need someone else’s code (package) in registry. To download that package, use:

npm install module-name@version

Installing a package by adding package dependency to package.json

Add a field called ‘dependencies’

{
  "name": "my_package",
  "version": "1.0.0",
  "dependencies": {
    "my_dep": "^1.0.0",
    "another_dep": "~2.2.0"
  }
}

Module

Module could be a:

• Folder with package.json
• A javascript file

When you use a module in your code, you will call require('module-name') in the script.