Node Basics

Run a Node App

terminal

node filename.js

You can execute node code in the terminal by typing

node 

This will give you a node command prompt

Node Modules

Nodejs api List

console.log('starting app');

const fs = require('fs');
const os = require('os');
 var user = os.userInfo();
 //console.log(user);
fs.appendFile('greet.txt', `hello${user.username}!` , (e)=>{
    if(e){
        console.log('error');
    }
});

Require your Own Files

const notes = require('./notes.js');

Notes.js file

module.exports.addNote = (a, b)=>{
var c = a + b;
return c;
};

Call the file in the app.js file

console.log('starting app');

const fs = require('fs');
const os = require('os');
const notes = require('./notes.js');
 var user = os.userInfo();
 var ret = notes.addNote(5,255);
//  console.log(user);
fs.appendFile('greet.txt', `hello${user.username}! you are ${ret}.` , (e)=>{
    if(e){
        console.log('error');
    }
});

Use external packages in your project

Go into the project directory

npm init
// answer questions. his will create a json file

Installing lodash Lodash is a set of handy utilities

npm install lodash --save
// the --save flag will update the content of the json file

Lodash API

To reload your project with all the necessary modules

npm install
// this will look in the package json file and reload all necessary modules

Install NODEMON to automatically reload your app

npm install nodemon -g

Install Yargs for parsing

npm install yargs@4.7.1 --save