NodeJS is saying 2-2322873 2526 56837 2 AND LL-PROG

NodeJS Debugging Example

const debug = require('debug')('nameOfDebugVar');
console.log("Var Val through the debugger");
let myArray= [].fill(120,0,10000);
let secondArr = myArray.map(elem => item*5);
debug("POST LOOP");

HOW TO RUN

DEBUG=nameOfDebugVar node nameOfFile.js

How To Get the FE communicate with the BE:

• SOAP
• REST

Folder Structure Of A NodeJS App

  ├──  /models  
  ├──  server.js
  ├──  node_modules
  ├──  package-lock.json
  ├──  package.json

Important Modules in NodeJS You Must Know

1. HTTP(built-in): Allow NodeJS to transfer data over the HTTP Protocol to use it use the require keyword

require('http');

2. Express: Node.js web application framework tool that helps with development of web and mobile applications

require('express');

3. MySQL: NodeJS Driver to work and connect with the relational database MySQL

require('mysql');

4. Dot-env: NodeJS Driver which enables you to load environment variables from a file

require('dotenv');

5. Nodemon: A Live server for your NodeJS application. Restarts automatically when any changes take place placed in your package.json file

npm install -g nodemon

6. Debug: A JS Debugging utility for your NodeJS application

npm install debug

7. Passport: An authentication middleware for you NodeJS application

npm install passport

Example of Authentication using PassportJS in your NodeJs App using A Post Request

app.post('/login',
  passport.authenticate('local', { successRedirect: '/',
                                   failureRedirect: '/login' })
);

8. Bcrypt: Library used to Hash Password in Your Application

npm install bcrypt

9. Mongoose: MongoDB Object Modeling Package which allows MongoDB to work with NodeJS

npm install mongoose

Usage

//In NodeJS
const mongoose = require('mongoose');

//ES6 Notation
import mongoose from 'mongoose';

• A DB Model Using Mongoose library thanks to its Schema Interace

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const FirstPost = new Schema({
  author: ObjectID,
  lovesDJ: Boolean,
  dateHeWatchedBD: Date,
  thingsHeLoves: Array,
  favSaying: String
});

• I can also use Input Validation before saving the data into my DB

const Comment = new Schema({
  name: { type: String, default: 'hahaha' },
  age: { type: Number, min: 18, index: true },
  bio: { type: String, match: /[a-z]/ },
  date: { type: Date, default: Date.now },
  buff: Buffer
});

// a setter
Comment.path('name').set(function (v) {
  return capitalize(v);
});

// middleware
Comment.pre('save', function (next) {
  notify(this.get('email'));
  next();
});

How To Connect MongoDB with NodeJS

0. Register First At MongoDB and Select A Plan
1. Create Your Cluster
2. Add A User
3. Select one of the two scenarios:

a. Whitelist Any IP(ONLY FOR LEARNING PURPOSES)

b. Whitelist your IP

4. To Connect Your Application...Click on Connect Application
5. Select NodeJS as Your Driver
6. Add the connection string into your application code in the db.json file
7. Store your username and password in a .env file inside an environment variable and do not commit this file
8. To be safe add .env file to your .gitignore file so that Git Doesn't track it

• Usage:

const bcrypt = require('bcrypt');
const saltRounds = 10;
const myPlaintextPassword = 's0/\/\P4$$w0rD';
const someOtherPlaintextPassword = 'not_bacon';
//how to hash a password
bcrypt.hash(myPlaintextPassword, saltRounds, function(err, hash) {
    // Store hash in your password DB.
});

Folder Structure Of A MERN App[Non-Relational]

root  
  ├──frontend

      │────── node_modules
      
      │────── package.json
      
      │────── package-lock.json
      
      │────── .gitignore
      
      │────── debug.log
      
      │────── public     
            │────── favicon.ico
      
            │────── index.html
      
            │────── manifest.json
      │────── src
            │──────────── App.css
      
            │──────────── App.js
      
            │──────────── App.test.js
      
            │──────────── components
      ├── index.css
      
      ├── index.js
      
      ├── logo.svg

      └── serviceWorker.js
  ├──backend
      ├──  /controllers  
      
      ├──  server.js
      
      ├──  /models  
      
      ├──  /routes  
      
      ├──  server.js
      
      ├──  node_modules
      
      ├──  package-lock.json
      
      ├──  package.json

Folder Structure Of A PERN App[Relational]

root  
  ├── /frontend

      │────── /node_modules
      
      │────── package.json
      
      │────── package-lock.json
      
      │────── .gitignore
      
      │────── debug.log
      
      │────── /public     
            │────── favicon.ico
      
            │────── index.html
      
            │────── manifest.json
      │────── /src
            │──────────── App.css
      
            │──────────── App.js
      
            │──────────── App.test.js
      
            │──────────── components
      ├── index.css
      
      ├── index.js
      
      ├── logo.svg

      └── serviceWorker.js
  ├── /backend
      ├──  /controllers  
      
      ├──  server.js
      
      ├──  /models  
      
      ├──  /routes  
      
      ├──  server.js
      
      ├──  /node_modules
      
      ├──  package-lock.json
      
      ├──  package.json  
  ├── /model
      ├── /schema
          |── 375fanb.sql
          └── 429fanb.sql

File Structure of A NodeJS PRoject

root  
  ├──nodejs
    ├── src
        ├──  app.js --------------------- Application Entry Point
        ├──  /api-routes ---------------- Controller Layer: For API Routes
        ├──  /config -------------------- where you store your environment vars
        ├──  /loaders ------------------- loaders for startup modules
        ├──  /models -------------------- Data Access Layer: Database models
        ├──  /scripts ------------------  NPM scripts
        ├──  /services ------------------ Service Layer: Store Your business logic
        ├──  /subsribers ---------------- asynchronous Event Handlers
        ├──  /test ---------------------- For Unit Testing
        ├──  package-lock.json
        ├──  package.json

Use Nodemon so that it restarts the server whenever I make any changes

npm i -D nodemon

How To Run NodeMon

npx nodemon yourfilename.js

Use Concurrently to be able to run the backend and frontend concurrently

npm i -D concurrently

Basic Nodejs Application

const http = require('http'),
      
//this is a callback function
makeServer = function (request,response){
   //must you want http displayed I must include the http header with suitable content type
   response.writeHead(200,{'Content-Type':'text/plain'});
   response.write('Hello world');
   response.end();
},
      
server = http.createServer(makeServer);

server.listen(3000,()=>{
  console.log('Node server created at port 3000');
});

Routing Call It Server.js Used So That when The User hits a certain route it displays it

const http = require('http'),
      url = require('url'),
 
makeServer = function (request,response){
   let path = url.parse(request.url).pathname;
   console.log(path);
   if(path === '/'){
      response.writeHead(200,{'Content-Type':'text/plain'});
      response.write('Home Page');
   }
   else if(path === '/about'){
     response.writeHead(200,{'Content-Type':'text/plain'});
     response.write('About page');
   }
   else if(path === '/ftn'){
     response.writeHead(200,{'Content-Type':'text/plain'});
     response.write('429 page');
   }
   else{
     response.writeHead(404,{'Content-Type':'text/plain'});
     response.write('Error page');
   }
   response.end();
 },
server = http.createServer(makeServer);
server.listen(3000,()=>{
 console.log('Node server created at port 3000');
});

Building A RESTFul API With NodeJS And Express

• An API Endpoint is a function within your API that returns Data
• A RESTful API is an API whereby the server nor the client have no idea of the state(object) of one another
• By using this interface, different clients hit the same REST Endpoints, perform the same actions, and receive the same responses without minding the state of one another

How To Create A RESTful API

1. create a folder

mkdir nodejs_api

1a. navigate to the folder

cd nodejs_api

2. Run the command npm init to create our package.json file

npm init

3. Install My Middleware

npm install express --save

4. 3 necessary files for my app

touch server.js index.html users.js

5. Goto Your Users.js File

// I use module.exports so that every program in my app can use it
module.exports.users = [
 {
  name: 'Mark Ramiro',
  age : 19,
  occupation: 'Aerospace Engineer',
  graduated : false,
  classes : ['Calc3','EPII','ChemII']
 },
  
 {
  name: '55732',
  age : 24,
  occupation: 'Developer',
  graduated : true,
  classes : ['429','375','373']
 },
 {
  name: 'Mike',
  age : 34,
  occupation: 'Full Stack Developer',
  graduated : true,
  classes : ['CALC3','EPII','OChemII']
 },
]

6. I use express to create my server

const express = require('express'),
      server = express(),
      users = require('./users');

//setting the port.
server.set('port', process.env.PORT || 3000);

//Adding routes
server.get('/',(request,response)=>{
    /*
    this searches for the file and sends it to the browser
    dirname is my root folder where my server is running from
    */
 response.sendFile(__dirname + '/index.html');
});

//I use response.json to websites requesting the data in JSON format
server.get('/users',(request,response)=>{
 response.json(users);
});

//Binding to localhost://3000
server.listen(3000,()=>{
 console.log('Express server started at port 3000');
});

7. Create the index.html file

<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <title>Home page</title>
</head>
<body>
 <button>Get data</button>
<script src="https://code.jquery.com/jquery-3.2.1.min.js" integrity="sha256-hwg4gsxgFZhOsEEamdOYGBf13FyQuiTwlAQgxVSNgt4=" crossorigin="anonymous"></script>
 
  <script type="text/javascript">
  
    const btn = document.querySelector('button');
    btn.addEventListener('click',getData);
    function getData(e){
        $.ajax({
        url : '/users',
        method : 'GET',
        success : function(data){
           console.log(data);
        },
      
        error: function(err){
          console.log('Failed');
        }
   });
  } 
 </script>
</body>
</html>

8. In the root folder I run the below command to start my nodejs application

node server.js

9. You just created a NodeJS Crud App

Working with Files thanks to the FS Module

• The File System allows you to work with files on your local computer
  • To Use it here is how we import it

var fs = require('fs');

URL Module which allows me to use the url address and break it into sections

var url = require('url');

Events Module In NodeJS

• Every action you take on your computer is an action
• I can fire an event in NodeJS whenever a file gets opened or closed

var fs = require('fs');
var myfile = fs.createReadStream('./polaanfb.txt');
myfile.on('open', function () {
  console.log('The polanfb text file is open');
});

• I can also use the built-in events module that NodeJS provides me with

var events = require('events');
var eventEmitter = new events.EventEmitter();//how to instantiate an event emmitter object
var theEventHandler = function () {
  console.log('2526: I Contacted 7652626 to get an A in 1336 and contacted 35 to get an A in 429');
}
eventEmmitter.on('Something happened please fire this event.', theEventHandler);//Assigning eventEmitter to theEventHandler
//firing the event

//How to emit the event
eventEmitter.emit('Emitted!');

File Uploading thanks to fs, http and formidable module

var http = require('http');
var formidable = require('formidable');
var fs = require('fs');

How To Send An Email thanks to the Nodemailer module

var nodemailer = require('nodemailer');