Using Javascript in today's world

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Using JavaScript in Today’s WorldSudar MuthuResearch EngineerYahoo! Labs

http://sudarmuthu.comhttp://twitter.com/sudarmuthu

What is JavaScript?

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World’s most popular programming

language

Douglas Crockford - http://javascript.crockford.com/popular.html

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World’s most misunderstood programming

language

Douglas Crockford - http://javascript.crockford.com/popular.html

Who am I?

To talk about JavaScript

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Fan of Douglas Crockford

http://wp.me/p4WjA-pe

The JavaScript wedding invitation guy

;)http://wp.me/p4WjA-rK

Using JavaScript in the browser

Options

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• YUI• jQuery• MooTools• Backbone.js• Knockout.js• .. and a million others

When to use YUI

• You already know what JavaScript is

• To build full-fledged websites that have numerous components with interdependent dependencies

• You need lot of build-in widgets• Need to use design patterns• Need to have a maintainable

code

When to use jQuery

• If you are new to JavaScript• Want something that is light• Have a simple website with

lesser number of components• Need a quick solution and want

something that is easier to learn

When to use backbone.js

• Decouple data from the UI• Use a full fledged MVC in the

client side as well• Want to have multiple

views/clients (mobile, desktop, tablets etc)

• You have a clear understanding of JavaScript and also the MVC concepts

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Other special purpose libraries

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• Lime.js – HTML5 based game framework

• Processing.js – Data visualizations and interactive animations

• flot – JavaScript plotting library• Raphael – Vector graphics library

Using JavaScript in the server

Why JavaScript on the server

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• Homogenous Programming Experience

• Easy meta programming• Easy reflection• Object literals• Interpreted Langauge

What is node.js

• Event-driven• Non-blocking I/O• Asynchronous• Single-threaded• Light weight and efficient

Why node.js

Code like this

var result = db.query("select..");// use result

either blocks the entire process orimplies multiple execution stacks (threads).

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Why node.js

But a line of code like this

db.query("select..", function (result){ // use result});

allows the program to return to theevent loop immediately. No moreunnecessary threads.

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Demo

Demo of callback

// execute the callback after 2 secondssetTimeout(function () { console.log("World!");}, 2000);

// print in consoleconsole.log("Hello");

https://github.com/sudar/jsfoo/blob/master/callback.js

Demo of a server in node.jsvar http = require('http'); // require the http module

// create a serverhttp.createServer(function (req, res) { // call this function when a request is received res.writeHead(200, { 'Content-Type': 'text/plain' }); // send this as part of the response res.end('Hello World\n');}).listen(1337, "127.0.0.1"); // listen on port 1337

// debug informationconsole.log('Server running at http://127.0.0.1:1337/');

https://github.com/sudar/jsfoo/blob/master/http-server.js

When to use node.js

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• Writing highly concurrent server applications

• Sharing application logic between server and client

• Peer-to-peer web applications using websockets

• And node.js is available in Azure

Other options to consider

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• Rhino• Spidermonkey• Narwhal• Nitro

Using JavaScript in mobile applications

PhoneGap

HTML5 app platform that allows you to write native mobile applications using web technologies like HTML and JavaScript

Yes it works in Windows Phone 7 as well

When to use it?

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If you need to have one code base and develop mobile applications for

• Android• iOS• Blackberry• Window Phone• etc

Using JavaScript in desktop applications

Some options to consider

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• Windows metro apps• Yahoo Konfabulator• Cappuccino• Titanium• Couch DB

Other exoctic use cases

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• Control USB hid devices – node-hid

• Control Serial devices – node-serialport

• Control Arduino – noduino• Control Powerpoint presentations

Well, it’s all fine, but I don’t like

JavaScript Syntax

Then use

CoffeeScript

Demo

QuestionsSudar Muthu

http://sudarmuthu.comhttp://twitter.com/sudarmuthu