The document discusses the various applications of JavaScript in web development, server-side programming, and mobile applications, highlighting popular libraries and frameworks such as YUI, jQuery, and Node.js. It emphasizes when to use these tools based on project requirements and offers examples, including callbacks and server creation in Node.js. Additionally, it mentions desktop applications and exotic use cases for JavaScript, while providing resources for further exploration.

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

2. What is JavaScript?

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

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

5. Who am I?
To talk about JavaScript

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

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

8. Using JavaScript in
the browser

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

10. 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

11. 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

12. 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

13. 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

14. Using JavaScript in
the server

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

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

17. Why node.js
Code like this
var result = db.query("select..");
// use result
either blocks the entire process or
implies multiple execution stacks
(threads).

18. Why node.js
But a line of code like this
db.query("select..", function (result){
// use result
});
allows the program to return to the
event loop immediately. No more
unnecessary threads.

19. Demo

20. Demo of callback
// execute the callback after 2 seconds
setTimeout(function () {
console.log("World!");
}, 2000);
// print in console
console.log("Hello");
https://github.com/sudar/jsfoo/blob/master/callback.js

21. Demo of a server in node.js
var http = require('http'); // require the http module
// create a server
http.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 information
console.log('Server running at http://127.0.0.1:1337/');
https://github.com/sudar/jsfoo/blob/master/http-server.js

22. 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

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

24. Using JavaScript in
mobile applications

25. 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

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

27. Using JavaScript in
desktop applications

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

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

30. Well, it’s all fine,
but I don’t like
JavaScript Syntax

31. Then use
CoffeeScript

32. Demo

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