Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. It allows JavaScript to be used for server-side scripting, enabling developers to write scalable network applications using JavaScript. Some key features of Node.js include non-blocking I/O calls, asynchronous programming, and an event loop that handles concurrency. Popular uses of Node.js include real-time web applications with websockets, fast file uploads, and any application requiring real-time data processing.

1. Author: Bhushan Patil
Date: 08 Mar 2014

3. 
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Node.js or nodejs or “node” simply is
“server side JavaScript”
Node.js is software platform
for scalable server-side and networking
applications.
Allows you to build scalable network
applications using JavaScript on the serverside.
Node.js
V8 JavaScript Runtime

4. 

The V8 JavaScript Engine is an open
source JavaScript engine developed
by Google for the Google Chrome web
browser.
V8 compiles JavaScript to native machine
code (IA-32, x86-64, ARM,
or MIPS ISAs) before executing it, instead
of more traditional techniques such as
executing bytecode or interpreting it.

5. 
“JavaScript has certain characteristics that
make it very different than other dynamic
languages, namely that it has no concept of
threads. Its model of concurrency is
completely based around events.” - Ryan
Dahl (Author node.js)

6. 
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
A Web Framework
For Beginners – it’s very low level
Multi-threaded – You can think of it as
single threaded server

8. 
Node js is for real-time web
◦ Node shines in real-time web applications
employing push technology over websockets Vs
stateless-web based on the stateless requestresponse paradigm.


Uses event-driven asynchronous callbacks
Handles concurrency very well than other
traditional web server

9. Traditional way
var result = database.query("SELECT * FROM hugetable");
console.log("Hello World");
Vs
Asynchronous way
database.query("SELECT * FROM hugetable", function(rows) {
var result = rows;
});
console.log("Hello World");

11. var
max
var
for
i, a, b, c, max;
= 1000000000;
d = Date.now();
(i = 0; i < max; i++) {
a = 1234 + 5678 + i;
b = 1234 * 5678 + i;
c = 1234 / 2 + i;
}
console.log(Date.now() - d);
$a = null; $b = null; $c = null; $i = null;
$max = 1000000000;
$start = microtime(true);
for ($i = 0; $i < $max; $i++) {
$a = 1234 + 5678 + $i;
$b = 1234 * 5678 + $i;
$c = 1234 / 2 + $i;
}
var_dump(microtime(true) - $start);
Time comparison in milliseconds
It means PHP is 93% slower than Node.js!

13. 
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Websocket Server - like chat application
Fast File Upload Client
Ad Server
Any Real-Time Data Apps

15. 
No Need of separate Server
◦ it does not require a separate webserver like Apache
or Nginx or IIS. It has an inbuilt HTTP Server library
which makes it possible to run a webserver without
external software, and allowing more control of how
the webserver works.

Non-blocking code
◦ It does not execute line by line like other traditional
languages.

Asynchronous programming
◦ Every function in Node.js is asynchronous. Therefore,
everything that would normally block the thread is
instead executed in the background.

16. Blocking code
var contents = fs.readFileSync('/etc/hosts');
console.log(contents); //Stop process until complete
console.log('Doing something else');
Non-Blocking code
fs.readFile('/etc/hosts', function(err, contents) {
console.log(contents);
});
console.log('Doing something else');

17. Traditional way
var result = database.query("SELECT * FROM hugetable");
console.log("Hello World");
Asynchronous way
database.query("SELECT * FROM hugetable", function(rows) {
var result = rows;
});
console.log("Hello World");

19. var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');
If run at command prompt:
% node example.js
Server running at http://127.0.0.1:1337/
At browser: http://127.0.0.1:1337/
Hello World

21. 
npm, short for Node Package Manager, is
two things: first and foremost, it is an
online repository for the publishing of opensource Node.js projects; second, it is a
command-line utility for interacting with
said repository that aids in package
installation, version management, and
dependency management.

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Some of the most popular NPM modules today are:
Express - Express.js, a Sinatra-inspired web
development framework for Node.js, and the defacto standard for the majority of Node.js
applications out there today.
connect - Connect is an extensible HTTP server
framework for Node.js, providing a collection of
high performance “plugins” known as
middleware; serves as a base foundation for
Express.
socket.io and sockjs - Server-side component of
the two most common websockets components
out there today.

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Jade - One of the popular templating
engines, inspired by HAML, a default in
Express.js.
mongo and mongojs - MongoDB wrappers to
provide the API for MongoDB object databases in
Node.js.
redis - Redis client library.

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coffee-script - CoffeeScript compiler that allows
developers to write their Node.js programs using
Coffee.
underscore (lodash, lazy) – The most popular
utility library in JavaScript, packaged to be used
with Node.js, as well as its two counterparts,
which promise better performance by taking a
slightly different implementation approach.
forever - Probably the most common utility for
ensuring that a given node script runs
continuously. Keeps your Node.js process up in
production in the face of any unexpected failures.

25. // Include http module,
var http = require('http'),
// And mysql module
mysql = require("mysql");
// Create the connection.
// Data is default to new mysql installation and should be changed according to your configuration.
var connection = mysql.createConnection({
user: "root",
password: "",
database: "db_name"
});
// Create the http server.
http.createServer(function (request, response) {
// Attach listener on end event.
request.on('end', function () {
// Query the database.
connection.query('SELECT * FROM your_table;', function (error, rows, fields) {
response.writeHead(200, {
'Content-Type': 'x-application/json'
});
// Send data as JSON string.
// Rows variable holds the result of the query.
response.end(JSON.stringify(rows));
});
});
// Listen on the 8080 port.
}).listen(8080);

27. And many .....

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http://nodejs.org/
http://en.wikipedia.org/wiki/Nodejs
http://node.codeschool.com/
http://stackoverflow.com/questions/235381
8/how-do-i-get-started-with-node-js
http://code.tutsplus.com/tutorials/nodejsfor-beginners--net-26314