1. JavaScript Libraries
Ajax Experience - Oct 2006
John Resig (ejohn.org)

2. Question: How do you want
to write JavaScript?

3. 1) Plug-and-Play
• Drop in a “calendar widget” or “tabbed
navigation”
• Little, to no, JavaScript experience required.
• Just customize some options and go.
• No flexibility.

4. 2) Some Assembly
Required
• Write common utilities
• Click a link, load a page via Ajax
• Build a dynamic menu
• Creating interactive forms
• Use pre-made code to distance yourself
from browser bugs.
• Flexible, until you hit a browser bug.

5. 3) Down-and-Dirty
• Write all JavaScript code from scratch
• Deal, directly, with browser bugs
• Quirksmode is your lifeline
• Excessively flexible, to the point of
hinderance.

6. What we’ve just seen...
• Widgets
• Libraries
• Raw JavaScript

7. What we’ve just seen...
• Widgets
• Libraries
• Raw JavaScript

8. Why use a library?
• Makes JavaScript bearable
• Gets the job done fast
• Simplifies cross-browser support
• Sort of like C stdlib - no one just codes C
by hand

9. What kind of libraries exist?
Open Source Commercial
Atlas
Client/ AjaxCFC
Backbase for
Server Qcodo
Struts
Prototype
Dojo
Browser Backbase
jQuery
Only SmartClient
Mochikit
Yahoo UI

10. What kind of libraries exist?
Open Source Commercial
Atlas
Client/ AjaxCFC
Backbase for
Server Qcodo
Struts
Prototype
Dojo
Browser Backbase
jQuery
Only SmartClient
Mochikit
Yahoo UI

11. Open Source Libraries
Browser Only Client/Server
Scriptaculous
Task AjaxCFC
moo.fx
Specific Qcodo
Open Rico
Prototype
Dojo
General Ruby on Rails
jQuery
Purpose CakePHP
Mochikit
Yahoo UI

12. Open Source Libraries
Browser Only Client/Server
Scriptaculous
Task AjaxCFC
moo.fx
Specific Qcodo
Open Rico
Prototype
Dojo
General Ruby on Rails
jQuery
Purpose CakePHP
Mochikit
Yahoo UI

13. What should a library have?
• DOM Traversing/Manipulation
• Event binding
• Ajax Support
• Basic Animations

14. What should a library have?
• Some want complex controls
• Drag-and-drop
• Auto-complete search
• Others want language enhancements
• Object.extend()
• Array.each()
• DOM, Event, Effects, Ajax is a good middle-
ground

15. Secondary Features
• Documentation
• Community Support
• File Size
• Popularity

16. Secondary Features
(Practical)
• Documentation
• Community Support
• File Size
• Popularity (Esoteric)

17. The Libraries

18. Dojo

19. Dojo: Overview
• Started early 2005 by Alex Russell
• Large development community
• Lots of corporate backing (IBM, AOL,
Google)
• Big code base, tons of features

20. Dojo: Focus
• Building complete web applications
• A package heirarchy, e.g.:
dojo.html.addClass( ... )
• Focus has transcended into widgets
• Huge number of features

21. Dojo: DOM Support
• Good DOM Modification support - handles
many cross-browser issues
• DOM Traversal could be spruced up to
handle selectors
var each = dojo.lang.forEach;
var tables = document.getElementsByTagName("table");
each(tables, function(table){
each(table.getElementsByTagName("tr"), function(row,i){
if ( i % 2 == 1 )
dojo.html.addClass( row, "odd" );
});
});

22. Dojo: Events and Effects
• Events support is complete and cross
browser
• Good selection of generic animations
var link = dojo.byId("mylink");
dojo.event.connect(link, "onclick", myHandler);
function myHandler(evt) {
dojo.lfx.html.fadeHide( link, 500 );
}

23. Dojo: Ajax
• Its crown jewel
• Supports virtually any form of Ajax
communication that you can think of
• XMLHTTPRequest, IFrame, Flash
• Has excellent backwards compatability
• Built-in back button support

24. Dojo: Docs & Community
• Documentation: Not much.
In the middle of a major documentation
overhaul for 0.4.
• Community: Lively
Over 60+ mailing list posts/day.

25. Dojo: File Size & Popularity
• File Size: Large (100Kb compressed)
It’s highly recommended that you remove
unused modules.
• Popularity: Substantial
Backing from many corporate sponsors
(IBM).

26. Prototype

27. Prototype: Overview
• Started early 2005 by Sam Stephenson
• Incredibly popular, tied with Ruby on Rails’
popularity
• Development backed by 37 Signals

28. Prototype: Focus
• Improving the usability of the JavaScript
language
• Big emphasis on adding in ‘missing’
JavaScript features
• Clean structure, clean objects and ‘classes’

29. Prototype: DOM Support
• DOM Modification works quite well:
Insertion.Bottom(“list”,”<li>Another item</li>”);
• So does >DOM Traversing:
$$(“table tr”).invoke(“addClassName”,”row”);

30. Prototype: Events & Ajax
• Event binding just works: function(){
Event.observe(“button”,”click”,
alert(“Thanks for the click!”);
});
• So does Ajax:
new Ajax.Request(“test.html”, {
method: “GET”,
onComplete: function(res){
alert( res.responseText );
}
});

31. Prototype: Details
• Code quality is fantastic, great features
• No support for animations
• moo.fx
• Script.aculo.us
• Updates are very infrequent (most recent
release is over a year old)

32. Prototype: Docs & Community
• Documentation: None
Some 3rd party web sites document some
versions, no official documentation.
• Community: Distributed
Many bloggers love Prototype, little
centralized discussion (16 posts/day).

33. Prototype: File Size & Popularity
• File Size: Moderate (40KB)
Unfortunately, not easily compressible.
• Popularity: Strong
Constantly in use at major web sites - tied
to popularity of Ruby on Rails.

34. jQuery

35. jQuery: Overview
• Released January 2006 by John Resig
• Rapid rise in popularity
• Many developers across the globe

36. jQuery: Focus
• Improving the interaction between
JavaScript and HTML
• Finding elements then performing actions
• Highly-effective, short, code

37. jQuery: DOM Support
• DOM Traversing is great - CSS1-3 support
and basic XPath:
$(“div > p:nth-child(odd)”)
• DOM Manipulation too:
$(“#li”).append(“<li>An item</li>”);

38. jQuery: Events, Effects, and Ajax
• Events are fully functional:
$(“div”).click( showItem );
• And effects:
$(“#menu”).slideDown(“slow”);
• And Ajax!
$(“form”).submit(function(){
$(“#results”).load(“test.html”);
});

39. jQuery: Details
• Core features are limited to DOM, Events,
Effects, Ajax
• Other features can be added in via plugins
• Relatively new, compared to other libraries

40. jQuery: Docs & Community
• Documentation: Complete
Fully documented, complete API.
• Community: Vibrant
91+ Mailing List Posts/Day

41. jQuery: File Size & Popularity
• File Size: Small
About 16KB with everything.
• Popularity: Growing
Little corporate backing.
Lots of sites switching:
Drupal, MSNBC, Technorati, FeedBurner.

42. Mochikit

43. Mochikit: Overview
• Released July 2005 by Bob Ippolito
• Managed and sponsored by MochiMedia
• Developed to power their Mochibot web
site

44. Mochikit: Focus
• Designed to fulfill common activities (All
the way from low-level iteration to high-
level Drag-and-Drop)
• Hierarchical structure:
Mochikit.DOM.addElementClass(...)

45. Mochikit: DOM Support
• Only a couple DOM Traversal functions -
no selectors (possibly coming in 1.4):
$(“body”)
• Plenty of helper functions for DOM
modification:
A({href: "test.html"}, "Test Page");
removeElementClass(“item”, “hilite”);

46. Mochikit: Events and Effects
• Event structure uses signals & slots
terminology:
connect(“list”,”click”, function(){
alert(“List Clicked”);
});
• Plenty of visual effects too:
blindDown(“list”, { duration: 0.5 });

47. Mochikit: Ajax
• Ajax support is fully functional:
doSimpleXMLHttpRequest("http://example.com", {bar: "baz"});

48. Mochikit: Details
• Lots of features (Rounded corners, drag-
and-drop) - much like Dojo
• Been a while since the last official update
(April 2006)

49. Mochikit: Docs & Community
• Documentation: Mixed
Everything is physically documented, but
the quality is mixed (e.g: blindDown: Blind
an element down, restoring its vertical size)
• Community: Small
About 6 mailing list posts/day

50. Mochikit: File Size & Popularity
• File Size: Large (100KB, compressed)
It is recommended that you remove unused
components and re-compress the code.
• Popularity: Stagnant
After almost a year and a half of existence,
popularity has yet to surge.

51. Yahoo! UI

52. YUI: Overview
• Released Feb 2006 by Yahoo!
• Maintained and financed internally
• Attempt to standardize internal JavaScript

53. YUI: Focus
• Exposing, and solving, common
methodologies
• Looking for common idioms (Drag-and-
Drop, Calendar, Auto-Complete)

54. YUI: DOM Support
• DOM Traversal is minimal, no selectors:
YAHOO.util.Dom.get(“list”)
• DOM Modification is also minimal,
modification only (no DOM creation):
YAHOO.util.Dom.addClass(“list”,”hover”)

55. YUI: Events and Effects
• Full Event support:
YAHOO.util.Event.addEventListener(
“list”, “click”, function(){
alert(“List Clicked”);
});
• Animations are also customizable:
new YAHOO.util.Anim(“list”,
{ width: { from: 10, to: 100 } }, 1,
YAHOO.util.Easing.easeOut
);

56. YUI: Ajax
• Ajax connections are simple to setup:
YAHOO.util.Connect.asyncRequest(
'GET', “test.html”, function(){
alert(“File loaded”);
}, null
);

57. YUI: Details
• Namespaces can become quite verbose. It
is recommended that you copy namespaces
to other variables.
var dom = YAHOO.util.Dom;
• Closed development (Yahoo employees
only, no subversion repository)

58. YUI: Docs & Community
• Documentation: Excellent
Everything is thoroughly documented. Lots
of explanations, plenty of demos.
• Community: Moderate
Mailing List hovering around 28 posts/day.

59. YUI: File Size & Popularity
• File Size: 40KB (Compressed)
Code is quite modular, you can remove un-
used code easily.
• Popularity: Moderate
Many good bloggers talking about it.

60. Feature Summary
DOM Events Effects Ajax
Dojo / X / X
Prototype X X - X
jQuery X X X X
Mochikit / X X X
Yahoo UI / X X X

61. More Information
• Dojo: http://dojotoolkit.org/
• Prototype: http://prototype.conio.net/
• jQuery: http://jquery.com/
• Mochikit: http://mochikit.com/
• Yahoo! UI: http://developer.yahoo.com/yui/

62. Ajax Experience
Presentations
• Presentations on:
• Dojo
• Prototype & Scriptaculous
• jQuery
• Yahoo UI
• Go to one that sounds interesting and
enjoy!