Source: http://www.tutorialspoint.com/nodejs/

Node JS tutorial for beginners:

This repo contains basic examples for node JS as I started to learn node JS from today from above link.

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Chapter-1: Print Hello Word

Installation on UNIX/Linux/Mac OS X, and SunOS:

$ sudo apt-get install nodejs

To run any js file:

$ node js/hello.js

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Chapter-2: basicHTTPserver:

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Chapter-3: REPL Terminal:

REPL stands for Read Eval Print Loop

Starting REPL

$ node
> 1 + 3
4

You can use underscore _ to get the last result:

> var a = 1
undefined
> b = 4
4
> a+b
5
> var sum = _
undefined
> console.log(sum);sum;
5
5
>

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Chapter-4: npm:

Node Package Manager (npm)

$ npm --version
3.10.5

* To update it to the latest version
$ sudo npm install npm -g

Installing Modules using npm
$ npm install <Module Name>

eg:
$ npm install express
var express = require('express');


--> You can use following command to check all the modules installed globally:
Here we can find Package.json file path:
$ npm ls -g
$ npm ls

Attributes of Package.json

    name - name of the package

    version - version of the package

    description - description of the package

    homepage - homepage of the package

    author - author of the package

    contributors - name of the contributors to the package

    dependencies - list of dependencies. npm automatically installs all the dependencies mentioned
                    here in the node_module folder of the package.

    repository - repository type and url of the package

    main - entry point of the package

    keywords - keywords

* Updating a module
$ npm update express

* Search a module
$ npm search express

* Uninstalling a module
$ npm uninstall express

* Create a module
$ npm init
$ npm adduser
To publish module:
$ npm publish

If everything is fine with your module, then it will be published in the reporsitory and
will be accessible to install using npm like any other other Node.js module.
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Chapter-5: Callbacks Concept:

Callback is nothing just to tell nodeJS that please keep continue execution if blocking task come and
when blocking task will done call that function back.

Example are in js/Callbackdemo directory

$ node js/Callbackdemo/blockingRead.js

$ node js/Callbackdemo/asyncRead.js

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Chapter-6: Events Loop:

This is same concepts as async calls.
The functions which listens to events acts as Observers.
Whenever an event gets fired, its listener function starts executing.

Steps:  Import - Create - Bind - Fire

// Import events module
var events = require('events');

// Create an eventEmitter object
var eventEmitter = new events.EventEmitter();

// Bind event and even handler as follows
eventEmitter.on('eventName', eventHandler);

// Fire an event
eventEmitter.emit('eventName');

Execute Events Example:
$ node js/eventLoop.js

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Chapter-7: Event Emitter:

EventEmitter provides multiple properties like on and emit.
on property is used to bind a function with the event and
emit is used to fire an event.

This is same as publish and subscribe feature.

If listener is bind to and event means is subscribed that event.
It will get execute on respective event emit.
Here execution of events based on bind sequence.

For example:
$ node js/basicEventEmmiter.js

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Author:
Shailesh Rudra
Ahmedabad, Gujarat

email : [email protected]