1. JavaScript Libraries
John Resig - May 2008
http://ejohn.org/
http://twitter.com/jeresig/

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 all
of C by hand

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

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

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

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

13. Why these libraries?

14. Developer Survey
jQuery Prototype Yahoo UI Dojo
14%
32%
22%
32%
http://ajaxian.com/archives/nitobi-survey-results-on-ajax-
development

15. Google Trends
jQuery
Prototype
Dojo
Yahoo UI
http://google.com/trends?q=prototype+javascript%2C+jquery+javascript%2C+yui+javascript%2C+dojo+javascript&ctab=0&geo=all&date=all&sort=0

16. Others
• Only so much time in a day!
• MooTools
• ExtJS
• Ajax.NET

17. The Libraries

18. Prototype

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

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

21. Prototype: Details
• Code quality is fantastic, great features
• All animations (and interactions) are in
Scriptaculous
• Updated frequently
• Looking at Prototype 1.6.0.2

22. jQuery

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

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

25. jQuery: Details
• Core features are limited to DOM, Events,
Effects, Ajax
• Other features can be added in via plugins
• Looking at jQuery 1.2.6

26. Yahoo! UI

27. YUI: Overview
• Released Feb 2006 by Yahoo!
• Maintained and financed internally
• Attempt to standardize internal JavaScript
• Say ‘hi’ to Nate Koechley!

28. YUI: Focus
• Exposing, and solving, common
methodologies
• Looking for common idioms (Drag-and-
Drop, Calendar, Auto-Complete)
• Looking at Yahoo UI 2.5.1

29. Dojo

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

31. Dojo: Focus
• Building complete web applications
• A package heirarchy, e.g.:
dojo.addClass( ... )
• Focus has transcended into widgets (Dijit)
• Huge number of features
• Today we’re looking at Dojo 1.1.1

32. What should a library have?

33. Code Base
• Core Functionality
• DOM
• Events
• Ajax
• Animations
• User Interface Widgets

34. Development
• Good Architecture
• Open Licensing
• Wide Browser Support
• Small File Size

35. Project
• Development Team (Open, Funded)
• Code in SVN / Bug Tracker
• Good Unit Test Coverage

36. Documentation
• Full API Coverage
• Plenty of Tutorials
• Some Books
• Wide variety of Demos

37. Community
• Active Mailing List / Forum
• Support and Training
• Popularity

38. Most Important
Question:
• Does the JavaScript library help me to
write JavaScript.
• The style of the library and its API is very
core to this.
• Can really only be determined through
sitting down and playing with a library.

39. Code Base
• Core Functionality
• DOM
• Events
• Ajax
• Animations
• User Interface Widgets

40. Core Functionality
• Bare minimum needed to make a dynamic
“Ajax” web site:
• DOM (Traversal and Manipulation)
• Events
• Ajax
• Animations

41. DOM
• Traversal
• Using CSS selectors to locate elements
• Modification
• Create/remove/modify elements
• Having a DOM builder is important

42. DOM Traversal
• Prototype:
$$(“table > tr”)
• jQuery:
$(“div > p:nth-child(odd)”)
• Dojo:
dojo.query(“table tr:nth-child(even)”)
• Yahoo UI:
YAHOO.util.Selector.query('div p')

43. DOM Modification
• Prototype:
Insertion.Bottom(“list”,”<li>Another item</li>”);
• jQuery:
$(“#li”).append(“<li>An item</li>”);
• Dojo and Yahoo UI have weak support - no DOM
building capabilities, basic property modification

44. Events
• Support for simple event binding/removal
• Support for custom events is essential
• Prototype:
Event.observe(“button”,”click”, function(){
alert(“Thanks for the click!”);
});
• jQuery:
$(“div”).click(function(){
alert(“div clicked”);
});

45. Events (cont.)
• Yahoo UI:
YAHOO.util.Event.addEventListener(“list”, “click”, function(){
alert(“List Clicked”);
});
• Dojo:
dojo.connect(dojo.byId(quot;mylinkquot;), quot;clickquot;, function(){
alert(“Link clicked”);
});

46. Custom Events
• $(“#list”).bind(“drag”, function(){
$(this).addClass(“dragged”);
});
• $(“#test”).trigger(“drag”);

47. Ajax
• Request and load remote documents
• Prototype:
new Ajax.Request(“test.html”, {
method: “GET”,
onComplete: function(res){
$(‘results’).innerHTML = res.responseText;
}
});
• jQuery:
$(“#results”).load(“test.html”);

48. Ajax (cont.)
• Yahoo UI
YAHOO.util.Connect.asyncRequest(
'GET', “test.html”, function(data){
YAHOO.util.Dom.id(“results”).innerHTML = data;
}
);
• Dojo
dojo.io.bind({
url: quot;test.htmlquot;,
method: quot;getquot;,
mimetype: quot;text/htmlquot;,
load: function(type, data) {
dojo.byId(“results”).innerHTML = data;
}
});

49. Ajax (cont.)
• jQuery is only one capable of doing DOM
traversing over XML
• jQuery.get(“test.xml”, function(xml){
$(“user”, xml).each(function(){
$(“<li/>”).text( $(this).text() )
.appendTo(“#userlist”);
});
});

50. Animations
• Simple animations (hide/show/toggle)
• Provide elegant transitions
• No animations in Prototype Core (see
Scriptaculous, instead)
• jQuery:
$(“#menu”).slideDown(“slow”);

51. Animations (cont.)
• Yahoo UI:
new YAHOO.util.Anim(“list”, { width: { from: 10, to: 100 } }, 1,
YAHOO.util.Easing.easeOut
);
• Dojo:
dojo.fadeOut({ node: dojo.byId(“list”), duration: 500 });

52. Core Feature Summary
DOM Events Anim. Ajax
Prototype X X - X
jQuery X X X X
Yahoo UI / X X X
Dojo / X X X

53. User Interface Widgets
• Difficult to implement components, made
easy
• Commonly used, save duplication
• Some common components:
Drag & Drop, Tree, Grid, Modal Dialog,
Tabbed Pane, Menu / Toolbar, Datepicker,
Slider

54. User Interface Packages
• Only looking at officially-supported code:
• Prototype has Scriptaculous
• jQuery has jQuery UI
• Dojo has Dijit
• Included in Yahoo UI

55. Drag & Drop
• Drag an item from one location and drop in
an other
• Supported by all libraries

56. Tree
• A navigable hierarchy
(like a folder/file
explorer)
• In Dojo and Yahoo UI

57. Grid
• An advanced table (resizable, editable, easily
navigable)
• In Dojo and Yahoo UI

58. Modal Dialog
• Display confined content (usually drag &
droppable) and confirmation dialogs
• In Dojo,Yahoo UI, and jQuery

59. Tabbed Pane
• Multiple panes of content navigable by a
series of tabs
• In Dojo,Yahoo UI, and jQuery

60. Menu / Toolbar
• A list of navigable items (with sub-menus)
• In Dojo and Yahoo UI

61. Datepicker
• An input for selecting a
date (or a range of
dates)
• In Dojo,Yahoo UI, and
jQuery

62. Slider
• A draggable input for entering a general,
numerical, value
• In all libraries

63. Tons More!
• Color Picker (Dojo,YUI)
• Layout (Dojo,YUI)
• Auto Complete (Dojo, Proto,YUI)
• Selectables (Proto, jQuery)
• Accordion (Dojo, jQuery)
• WYSIWYG (Dojo,YUI)

64. Themeing
• A consistent look-and-feel for widgets
• jQuery,Yahoo UI, and Dojo provide
themeing capabilities
• jQuery’s and Yahoo UI’s are documented

65. Accessibility
• Taking in to consideration points from
ARIA (Accessible Rich Internet
Applications)
• Dojo is taking a solid lead, here
• jQuery received funding and is working on
ARIA integration to jQuery UI
• Yahoo is investigating ARIA

66. Development
• Good Architecture
• Open Licensing
• Wide Browser Support
• Small File Size
• Speed

67. Architecture
• Bottom Up (Prototype, jQuery)
vs. Top Down (Dojo,Yahoo UI)
• jQuery, Dojo, and Yahoo UI all use a single
namespace
• Prototype extends native objects (high
likelihood of inter-library conflict)
• jQuery is extensible with plugins
• Dojo uses a package system

68. Licensing
• All use liberal licenses
• MIT: (“Keep my name on the file”)
Prototype, jQuery
• BSD: (“...and please don’t sue me.”)
Yahoo UI, Dojo

69. Browser Support
• Everyone supports:
IE 6+, Firefox 2+, Safari 2+, Opera 9+
• Note:
• Most are in the process of dropping
support for Safari 2

70. File Size
• Serving your JavaScript minified + Gzipped
• Optimal level of compression and speed
• Core file size (in KB):
35.00
26.25
17.50
8.75
0
Prototype jQuery Yahoo UI Dojo

71. Speed
• Hard to quantify
• Currently the only point of comparison is
in CSS Selectors
• Speed varies across browsers
• Competition is strong (much faster than
what they use to be)
• DOM Modification, Events completely un-
compared

72. Project
• Development Team (Open, Funded)
• Code in SVN / Bug Tracker
• Good Unit Test Coverage

73. Development Team
• Prototype, jQuery, and Dojo all have open
development (anyone can contribute)
• jQuery,Yahoo UI, and Dojo all have paid,
full-time, developers working on the code
• All have paid, part-time, developers

74. SVN / Bug Tracker
• Prototype, jQuery, and Dojo all have code
in a public SVN repositories
• Yahoo UI’s development is private and is
limited to Yahoo employees
• They’re working to fix this!
• All libraries have a public bug tracker

75. Unit Tests
• All libraries have some automated unit
tests
• jQuery,Yahoo UI, and Dojo all have public
unit test URLs
• jQuery and Dojo have tests that can run in
Rhino

76. Documentation
• Full API Coverage
• Plenty of Tutorials
• Some Books
• Wide variety of Demos

77. API Documentation
• Prototype, jQuery, and Yahoo UI all have full
coverage
• jQuery provides runnable examples with
each API item
• Dojo’s coverage is improving - work in
progress (dojocampus.org, etc.)

78. Tutorials
• All libraries provide some tutorials
• jQuery,Yahoo UI, and Dojo have
screencasts/presentations
• Prototype: 6
• jQuery: 118 (English)
• Yahoo UI: 30+ (each component has at
least one)
• Dojo: 24

79. Books
• Prototype:
• Prototype and Scriptaculous in Action (Manning)
• Prototype and Scriptaculous (Pragmatic)
• jQuery:
• Learning jQuery (Packt)
• jQuery Reference Guide (Packt)
• Yahoo UI:
• Learning the Yahoo UI Library (Packt)
• Dojo: 3 books coming in 2008

80. Demos
• Yahoo UI provides a considerable number
of live demos and examples for all features
• jQuery provides live examples and a few
demo applications
• Dojo provides demo applications for their
widgets

81. Community
• Active Mailing List / Forum
• Support and Training
• Popularity

82. Mailing List / Forum
• Prototype, jQuery, and Yahoo UI have
mailing lists
• Prototype: 23 posts/day
• jQuery: 76 posts/day
• Yahoo UI: 56 posts/day
• Dojo has an active forum

83. Support and Training
• Dojo provides paid support and training
(via Sitepen)
• jQuery provides paid jQuery UI support
and training (via Liferay)

84. Popularity
• Who uses what:
• Prototype: Apple, ESPN, CNN, Fox News
• jQuery: Google, Amazon, Digg, NBC, Intel
• Yahoo:Yahoo, LinkedIn, Target, Slashdot
• Dojo: IBM, AOL, Mapquest, Bloglines

85. Common Questions

86. Why don’t the libraries
merge?
• It’s really hard to have a unified backend
• Everyone fixes different bugs
• Everyone implements *slightly* different
features
• A combined library would be massive

87. Can common
components be made?
• Possibly.
• Again hit the problem of finding the correct
mix of features and bugs.
• Component would have to be very special.

88. Why not make a unified
API?
• A library’s API helps makes it unique
• Embody different philosophies
• Combing all of them and trying to please
everyone creates a unified, boring, mess

89. More Information
... questions?
• Prototype:
http://prototypejs.org/
• jQuery:
http://jquery.com/
• Yahoo UI:
http://developer.yahoo.com/yui/
• Dojo:
http://dojotoolkit.org/