NPM: node package manager

1. A library of thousands of packages published by other developers that we can use for free

2. A command line tool to easily install and manage those packages in out node projects

examples: Jokes and Color

https://www.npmjs.com/package/give-me-a-joke

https://www.npmjs.com/package/colors

Step 1: install packages:

npm i give-me-a-joke

npm i colors

Step 2: require package name

Step 3: call functions accroding to particular API

//index.js
const jokes = require("give-me-a-joke");
const colors = require("colors");

jokes.getRandomDadJoke(function (joke) {
    console.log(joke.rainbow);
});

• Adding Global Packages

npm i -g cowsay在大路径下面引入global package

npm link cowsay在单个小路径下link引入的package名称，然后在js文件里面require

• npm init，生成package.json文件：

• 引入包

• 使用别人的开源代码，包含package.json文件，但是不包含node_modules文件，在package.json文件路径下“npm install”，就会自动生成相关依赖文件node_modules。
     npm install: 在package.json同一路径下
• go ahead and install dependencies basaed upon package JSON files, then we can get a file called node_modules