Introduction to Node.js and how to create simplest web application using ExpressJs

1. Jitendra Zaa

2. What is Node.js
 Is Light Weight Server
 Used to create scalable network based application
using JavaScript like Syntax

3. Why Node.js
 Uses same JavaScript engine which is used by Google Chrome
Browser “V8 JavaScript Runtime”.
 Mostly for very Low level network programming
 Very fast because most of modules created in C language
 Single Threaded application
 It is not web development framework and not a complete
replacement of PHP or Ruby like language.
 However, there are few modules available like “Express.js” to
create Single page applications

4. What's Different about Node.js
 Most expensive job for processor is reading content
from Harddisc (IO Jobs).
 Most programming languages wait for read/write to
complete and then executes next statement.

 Unlike others, node.js executes IO operations
asynchronously and callback method is used to
resume an operation which needs to be completed
after IO.

5. How to Install
 Install Node.js SDK from http://nodejs.org/

6. First Program – Hello World
// Load the http module to create an http server.
var http = require('http');
// Configure our HTTP server to respond with Hello World to all requests.
var server = http.createServer(function (request, response) {
response.writeHead(200, {"Content-Type": "text/plain"});
response.end("Hello Worldn");
});
// Listen on port 8000, IP defaults to 127.0.0.1
server.listen(8000);
// Put a friendly message on the terminal
console.log("Server running at http://127.0.0.1:8000/");

7. Running First Program
 Save Code shown on previous slide in file named
“HelloWorld.js”
 Open Command Prompt and run file with Node
command

8. Running First Program (cont)
 On Console, you would see message saying Server is
running.
 And we open address “http://localhost:8000/” in
browser, Hello world will be displayed

9. Creating Web Application

10. ExpressJs - Install Node Modules
 Express (http://expressjs.com/) is mostly adapted web
module for Node.js to create Single page websites.
 To Install ExpressJs Module, create “Package.json” in
folder
 “Package.json” has metadata informations for module
needs to be installed

11. Package.json
{
"name": "hello-world",
"description": "hello world test app",
"version": "0.0.1",
"private": true,
"dependencies": { "express": "3.x" }
}

12. Installing ExpressJs Module
After creation of “Package.json”, run command
npm install
in folder where “package.json” exists.

13. Simplest Web Application in
Node.js
var express = require('express');
var app = express(); // create our app w/ express
app.configure(function() {
app.use(express.logger('dev')); // log every request to the console
app.use(express.json()); // Do not use bodyParser() , Instead use json() and urlencoded()
app.use(express.urlencoded()); // bodyparser() is depreciated from Express 3.0
});
app.get('/2', function(req, res) {
res.sendfile(__dirname + '/Page2.html');
});
app.get('*', function(req, res) {
res.sendfile(__dirname + '/Test Arrow.html');
});
app.listen(8080); //Listen on Port
console.log("App listening on port 8080");

14. Creating Sample HTML Files
 Save code of previous slide, in file named
“ExpressDemo.js”
 Html File 1 – “Test Arrow.html”
 Html File 2 – “Page2.html”
 Start Node application using command “node
ExpressDemo.js”

15. Running Web application
 Initially on navigation at http://localhost:8080/ we will
see content of “Test Arrow.html” file.
 If we change URL with something like
http://localhost:8080/2 , node server will post content
of file “Page2.html”

16. Output

17. Thanks !!!