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Using JavaScript in Today’s World Sudar Muthu Research EngineerGO BIG! Yahoo! Labs http://sudarmuthu.com http://twitter.com/sudarmuthu

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What is JavaScript?

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World’s most popularprogramming language Douglas Crockford - http://javascript.crockford.com/popular.html

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World’s most misunderstoodprogramming language Douglas Crockford - http://javascript.crockford.com/popular.html

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Who am I?To talk about JavaScript

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Fan of Douglas Crockford http://wp.me/p4WjA-pe

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The JavaScript wedding invitation guy ;) http://wp.me/p4WjA-rK

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Using JavaScript inthe browser

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

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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

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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

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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• Lime.js – HTML5 based game framework• Processing.js – Data visualizations and interactive animations• flot – JavaScript plotting library• Raphael – Vector graphics library

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Using JavaScript inthe server

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Why JavaScript on the server• Homogenous Programming Experience• Easy meta programming• Easy reflection• Object literals• Interpreted Langauge

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What is node.js• Event-driven• Non-blocking I/O• Asynchronous• Single-threaded• Light weight and efficient

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Why node.jsCode like thisvar result = db.query("select..");// use resulteither blocks the entire process orimplies multiple execution stacks(threads).

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Why node.jsBut a line of code like thisdb.query("select..", function (result){ // use result});allows the program to return to theevent loop immediately. No moreunnecessary threads.

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Demo

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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

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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 Worldn);}).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

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When to use node.js• 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

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Other options to consider• Rhino• Spidermonkey• Narwhal• Nitro

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Using JavaScript inmobile applications

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PhoneGapHTML5 app platform that allows you towrite native mobile applications usingweb technologies like HTML andJavaScriptYes it works in Windows Phone 7 aswell

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When to use it?If you need to have one code base anddevelop mobile applications for• Android• iOS• Blackberry• Window Phone• etc

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Using JavaScript indesktop applications

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Some options to consider• Windows metro apps• Yahoo Konfabulator• Cappuccino• Titanium• Couch DB

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Other exoctic use cases• Control USB hid devices – node-hid• Control Serial devices – node- serialport• Control Arduino – noduino• Control Powerpoint presentations

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Well, it’s all fine, but I don’t likeJavaScript Syntax

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Then useCoffeeScript

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Demo

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Questions Sudar Muthu http://sudarmuthu.com http://twitter.com/sudarmuthu