Node JS Express : Steps to Create Restful Web App

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Node JS Express - Steps to create Restful Web App

www.edureka.co/mastering-node-jsSlide 2
The Importance or Reason for this Course
Node.js is a platform for building high performance, event-driven, real-time and scalable networking
applications just using javascript.
You will receive hands-on training in Node.js, building networking and web based applications that are far
superior and efficient than your regular languages.
And the best part : It's all in Javascript – on the server or on the client – Javascript Everywhere!
This course is designed to help you learn this amazing platform with great ease, with the help of hands-on
training, code snippets, live sessions and expert support.

Demand for this Course
Javascript is an ubiquitous language known by millions of developers worldwide. When using Node.js,
Javascript becomes a fully-functional server side programming language that is well suited for making real-time
business apps and APIs
More and more employers & entrepreneurs are switching their technologies to Node.js
Cases in point : Walmart, Paypal/Ebay, Microsoft, LinkedIn, Yahoo, Yammer (Now part of Microsoft) and the list
is never ending.

Job Trends
Salaries for Node.js Developers are already in the $60,000 range and much more.
From the graph below : The number of jobs are skyrocketing.

LIVE Online Class
Class Recording in LMS
24/7 Post Class Support
Module Wise Quiz
Project Work
Verifiable Certificate
Course Features

Objectives
At the end of the session you will be able to learn:
Nodejs express
Creating Restful Web App
NPM
Templates in Express

What is Node.js ?
It is an Open-Source, Cross-Platform runtime environment for networking applications
It is built on top of Google Chrome’s JavaScript Runtime : V8
This lets us build fast, highly scalable networking applications just using JavaScript
It is an Asynchronous Event driven framework
Guess What ?
» IT’s SINGLE THREADED !!
» No worries about : race conditions, deadlocks and other problems that go with multi-threading.
» “Almost no function in Node directly performs I/O, so the process never blocks. Because nothing blocks,
less-than-expert programmers are able to develop scalable systems.” - (courtesy : nodejs.org)

What is Node.js ?
Node.js is Event Driven. Uses the Event Emitter model
Just because Node.js is Single Threaded does not mean you can’t have multiple cores in your application. We
can fork or spawn child processes from the main node process any time
» This lets us even fire shell commands or even start up another Application straight from your Node.js
Application

Your First Node.js Program
Thats right : since we deal with good ol’ Javascript. Lets write our first program :
function yooohoooWorld()
{
console.log(‘Yooddleeeyodleeyodleeeeooooo World!!!’);
}
yooohoooWorld();
Copy that onto a new file and save it with a “.js” extension
Go to command line, cd to the folder with that file and run : node example.js
In fact, Node.js comes with an REPL (Read-Eval-Print-Loop) : a simple command line tool to interactively run
Javascript and see the results. Just type “node” on the command line and hit enter

Basics of Node.js : npm
npm used to stand for Node Package Manager. Now it stands for nothing. Its actually not an acronym. npm is
not a Node.js specific tool any more
npm is a registry of reusable modules and packages written by various developers
» Yes, you can publish your own npm packages
There are two ways to install npm packages :
» Locally : To use and depend on the package from your own module or project
» Globally : To use across the system, like a command line tool
Installing a package locally :
» The package is easily downloaded by just saying npm install <packagename>
» This will create a node_modules directory (if it does not exist yet) and will download the package there
» Once installed you can use it in any js file of your project by saying
» var obj = require(‘packagename’);

Tip: Next time you want to clone or
copy your project to another server,
just copy the code you wrote and
the package.json file. Then run
npm install on that server
Installing a package locally ...contd. :
» Another way to save packages locally is by using a package.json file.
» Advantage > ?
» Once you have a package.json file in your directory, and you run npm install, all package names listed in
there are downloaded
» Thats really cool. Because now, your build is “reproducible”
» package.json :
{
"name": "demo-app",
"version": "1.0.0"
}
» Then npm install --save <packagename>. This adds the package name to the package.json

Installing a package locally ...contd. :
You can also manually enter the name of the package and the version number to your package.json file like so :
{
"name": "demo-app",
"version": "1.0.0",
"dependencies": {
"packagename": "^2.4.1"
}
}

To install an npm package globally :
just run npm install -g <packagename>
To update or uninstall a globally installed package, just
run npm update or npm uninstall with the -g option
Tip: Most often when globally installing a package you would need root access :
→ On Windows the following command will open the Command Line as
Administrator

→ Tip: Most often when globally installing a package you would need root
access :
» Another alternative for Windows which will come in handy is
installing some other Command Line alternative like Console2
(http://sourceforge.net/projects/console/) or ConEmu
(http://www.fosshub.com/ConEmu.html) , etc.
» For Linux/Unix/Mac : sudo npm install -g <packagename>

Express JS
Express JS : Web Framework for Node.js. It is an npm package
To install : npm install express //in the main project folder
Express JS also provides a tool to create a simple folder structure for your app : express-generator :
npm install express-generator -g //To be installed globally
» Now, saying express newapp will create a project called newapp in the current working directory along
with a simple folder structure.
» The dependencies will then be installed by doing a cd newapp and then npm install
» To run the app
» node ./bin/www // This is where the server is run and listening on a port

Express JS : Templates
By default Express supports the Jade Template Engine for the HTML Views.
What is an Javascript Template Engine : it is a framework to help bind data to your HTML views
Why do you need one ?
» Helps you easily bind data from the back end with the HTML view
» Helps in bundling HTML code into reusable modules/layouts
» Adds basic conditionals & iterations / loops to your HTML. HTML does not support “If -Else” or “for”
loops.
Many Javascript Template Engines are available : Jade, Handlebars, Hogan, EJS, etc.

Express JS : Templates
To use the default Jade template engine continue as described before
To use Handlebars,
express --hbs newapp
To use Hogan,
express -H newapp or express --hogan newapp
To use EJS,
express -e newapp or express --ejs newapp
If you want to use a css engine like stylus or less add the following option : --css <engine>
where <engine> can be less or stylus or compass
You can use the --force or -f option to force the express generator on a non-empty directory

Express JS : Jade
Jade is a simple Javascript Template engine for writing HTML. No config has to be set up for ExpressJS since it
is the default view engine
However, Jade has a different syntax as compared to HTML, may not preferred by some developers.
Example of Jade syntax :
JADE
html
head
title My App Title
body
h1= pageHeaderVar
div.className
p.
some
content
HTML
<html>
<head>
<title> My App Title
</title>
</head>
<body>
<h1>Page Header</h1>
<div class=”className”>
<p>
some
content
</p>
</div>
</body>
</html>

Express JS : Handlebars
Handlebars is a Javascript Template Engine having a much more simple HTML like syntax. Actually Handlebars
templates are HTML with a few added operators and some javascript functions available for use.
To use Handlebars in Express JS, we use the “hbs” npm package which is a simple wrapper for Handlebars.js.
To use this as the view engine in place of Jade, we first have to npm install hbs if you have not already used
the express-generator’s --hbs option to express command.
Set view engine in app.js to app.set(‘view-engine’,’hbs’)
For the most part, Handlebars is nothing but HTML, intermingled with Handlebar Expressions. A Handlebar
Expression is, {{ with some expression/variable or content followed by }}.

Express JS : Handlebars
So if a Handlebar template is being rendered and an object, {greeting: “Hello World”, subgreeting: “Hey folks
I’m using HBS”} is passed to it, the handlebar syntax will look something like this :
//- index.hbs
<div>
<h1>{{greeting}}</h1>
<h5>{{subgreeting}}</h5>
</div>
//After Rendering :
<div>
<h1>Hello World</h1>
<h5>Hey folks I’m using
HBS</h5>
</div>

Express JS : A Simple Express Application
var express = require(‘express’);
var app = express();
app.get(‘/’,function(req,res){
res.send(‘Hello World !!”);
})
app.listen(3000,function(){
console.log(‘Express Server listening on port 3000);
})

DEMO

Course Topics
→ Module 7
» Forks, Spawns and the Process Module
→ Module 8
» Testing in Node.js
→ Module 9
» Node.js in the Tech World
→ Module 1
» Introduction to Objects in Javascript & Node.js
→ Module 2
» Modules / Packages
→ Module 3
» Events & Streams
→ Module 4
» Network Communication & Web Technology in
Node.js
→ Module 5
» Building a Web Application
→ Module 6
» Real-time Communication

Questions

Node JS Express : Steps to Create Restful Web App

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