nodejs class

* Module:
+ nodemon reload, automatically
+ Express 3.x is a light-weight web application framework to help organize your  
  web application into an MVC architecture on the server side.
+ body parser : its a middleware for parsing JSON
+ express-fileupload : uploading a file


api crud:
https://www.youtube.com/watch?v=4fWWn2Pe2Mk
form crud:
https://scotch.io/courses/build-a-nodejs-website/course-introduction

What is Node Js:

Nodejs is a C++ application.
Because v8 engine written in c++

Node.js is an open source server environment.

Node.js allows you to run JavaScript on the server.

Node.js is an open source server environment.

V8 engine:

  Code that we write on our computers is converted or compiled into machine code.
  V8 is a powerful open source Javascript engine provided by Google.
  The V8 engine is written in C++ and used in Chrome and Nodejs.
  v8 engine convert javascripts into machine code.

Node.js is free

Node.js runs on various platforms

Node.js can generate dynamic page content

Node.js can create, open, read, write, delete, and close files on the server

Node.js can collect form data

Node.js can add, delete, modify data in your database

npm is node package manager



download:

download https://nodejs.org/en/ latest feature


Run :

cmd> node -v

cmd> touch filename.js (write console.log("ok"))

cmd> node filename


* Global Object:

buit in objects for work.
all js window object can run in nodejs.

* Clock Project:

var time = 0;

setInterval(function(){

  time += 1;
  
  console.log(time+'You have Passed');
  
},1000);


* Find directory:
  
  console.log(__dirname);
  console.log(__filename);
  
* simple function
 
 function abc(x){
   console.log(x);
 }
 
 abc(10);

* call back function:
    
  function callBackFunc(mainfun){
    mainfun();
  }

  var mainfun = function(){
   console.log("main function");
  }

  callBackFunc(mainfun);
  
  
  
* http built in module (use port):
 
  var http = require('http');
  
  http.createServer(function (req, res) {
  
    res.write('Hello World!');=
    
    res.end();
    
  }).listen(8080); 
  
  hit : http://localhost:8080/
  
  You can set header type:
  res.writeHead(200, {'Content-Type': 'text/html'});
  
  you can get uri:
  res.write(req.url);
  
  
  
* fs built in module (file handle):

  var http = require('http');
  var fs = require('fs');
  
  http.createServer(function (req, res) {

    fs.readFile('a.html', function(err, data) {
      res.writeHead(200, {'Content-Type': 'text/html'});
      res.write(data);
      res.end();
    });

  }).listen(8080); 
  

* file built in create:

  fs.open('mynewfile2.txt', 'w', function (err, file) {
	   if (err) throw err;
	   console.log('Saved!');
  }); 
  
* file write:

  
  fs.writeFile('mynewfile2.txt', 'Hello content!', function (err) {
	  if(err) throw err;
	  console.log('Saved!');
  }); 


* export built in module: 

  module is library.
  Node.js has a set of built-in modules which you can use without any further installation.
  module.exports use for available var in full page.
  
  common.js:
  
  var counter = function (arr){
   return "Your array lenght is : "+arr.length;
  }

  module.exports = counter;
  
  
  main.js:
  
  var counter = require('./common');
  console.log(counter(['a','b','c']));
  
  
  
  
* multiple exports built in module:

  abc.js :
  
  var msg = require('./common');

  console.log(msg.counter(['a','b','c']));

  console.log(msg.messages("abc"));
  
  
  common.js: 
  
  var counter = function (arr){
    return "Your array lenght is : "+arr.length;
  };

  var messages = function(data){
    return data;
  };


  module.exports.counter = counter;
  module.exports.messages = messages;
  
  
  
 * external module npm).
   Downloading a package is very easy.
   Open the command line interface and tell NPM to download the package you want.
   I want to download a package called "upper-case":

   folder_name > npm init
   folder_name > npm install upper-case
   
   var uc = require('upper-case');
   res.write(uc("Hello World!"));
   
   
* create a form:

var http = require('http');

http.createServer(function (req, res) {

  res.writeHead(200, {'Content-Type': 'text/html'});
  res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
  res.write('<input type="file" name="filetoupload"><br>');
  res.write('<input type="submit">');
  res.write('</form>');
  return res.end();
  
}).listen(8080); 



* database connection :

  cmd > npm install mysql 

  
  var mysql = require('mysql');

  var con = mysql.createConnection({
     host: "localhost",
     user: "root",
     password: ""
  });

  con.connect(function(err) {
     if (err) throw err;
     console.log("Connected!");
  });