Handy npm commands

1. use npm init to generate a package.json file for the application

2. use npm install --save flag to mark the package as an application dependency.

for example when i ran npm install express --save, the process will automatically add express to the
dependencies section.

use npm install --save-dev to install the library for the development of an application only

{

  "name": "first_express_project",

  "version": "1.0.0",

  "description": "first web project build with express",

  "main": "main.js",

  "scripts": {

    "test": "echo \"Error: no test specified\" && exit 1"

  },

  "author": "Dan Deng",

  "license": "ISC",

  "dependencies": {

    "express": "^4.17.1"

  }

}

3.  run npm docs library name to access the library documentation.

for example npm docs express will launch the default web browser to http://expressjs.com.

4. npm i nodemon -g to install the node monitor package to force restart the application. after any change to the project.
use the following configuration to setup nodemon to run the application

 "scripts": {

    "start":"nodemon main.js",

    "test": "echo \"Error: no test specified\" && exit 1"

  },

then run npm start to launch the application.

λ npm start

> first_express_project@1.0.0 start C:\code\Node\first_express_project
> nodemon main.js

[nodemon] 2.0.4
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node main.js`
The express server has started and is listening on port number : 3000