Choosing a JavaScript library

Intro

One of Kauri's goals is not to reinvent the wheel until necessary. A modern web application framework these days needs a JavaScript library to provide common, reusable functionality and save us from writing lots of repetitive code. Libraries also provide a layer of abstraction, thus hiding browser differences.

We do not want to write one ourselves because it saves time to use an existing one, plus these libraries are more likely to contain fewer bugs because of the significant user base.

Because of the multitude of Javascript libraries, we started our search by selecting only the most-used, most-popular and up-to-date Ajax-enabled libraries.

The contestants

The pros and cons are (possibly biased) opinions collected from blogs and fora, or features promoted on the homepages.

Disqualified:

• MochiKit: seems to be deserted
• Rico: dying community, low support

Our requirements for a JS library within Kauri

1. base for client-side restletport
2. cross-browser issues:
• syntax
• DOM model
• event model
3. dynamic loading of js-files
4. event binding
5. unit testing
6. (widgets, effects)
7. integration of external widgets (Simile)
8. size, stability, maturity
9. compression
10. i18n, L10n

Popularity (by number of searches)

The qooxdoo framework didn't have enough search volume to show up on the graph.

Language

There are arguments why a js framework should not try to be an OO programming language (see *,* and *).

XmlHttpRequest

All libraries contain specialized methods for Ajax calls, with support for GET and POST requests, parameters and callback functions. IFrame I/O is mostly used for file upload.

CSS Framework integration

• jQuery + Blueprint

GWT wrappers

GWT + ExtJS: gwt-ext, MyGWT
GWT + Dojo: Tatami
GWT + Script.aculo.us: Script.aculo.us integration

Java + qooxdoo: QWT

JavaScript Native Interface (JSNI)

Test 1: GWT Integration

• jQuery: Google Maps the jQuery Way
• YUI: Google Maps + Yahoo UI Lib (YUI) = Mashup fun
• qooxdoo: Google Maps widget
• ExtJS: Adding a Google Map to a Tab or Window
• MooTools: GMapsOverlay, google-maps-lightbox
• Prototype: gplotter

Test 2: Simile

Simile Timeline and Timeplot are based on jQuery 1.2.1, which could cause conflicts.

• Dojo: Dojo and TimeLine
• jQuery: How to make Timeline not conflict with jQuery
• GWT: gwtsimiletimeline
• Prototype: Timeline

Test 3: i18n support

• Dojo: has a specific i18n module (*).
• jQuery: no built-in i18n support. Localization is available for the datepicker-widget
• Prototype: no built-in i18n support.
• ExtJS: localization support (*, *).
• YUI: no built-in i18n support, there is however an internationalization plugin (*).
• MooTools: no built-in i18n support.
• qooxdoo: i18n and L10n are fully supported (*).
• GWT: internationalization support (*).

Test 4: Support for Unit testing

• qooxdoo: testrunner
• Prototype: there's a test framework that can be extended for custom unit tests (*).
• jQuery: internal test framework
• Dojo: has a unit testing harness, D.O.H.
• MooTools: no unit testing
• Ext JS: no unit testing (*, *)
• YUI: YUI Test
• GWT: JUnit integration

Standalone js unit test tools:

• Crosscheck
• Testcase (Prototype-based)
• Selenium
• JsUnit

Test 5: Building a custom widget

jQuery: Writing your own plugins
Dojo: Creating new Dojo Widget, Dojo Custom Widget Tutorial, Create a Custom Javascript/AJAX Widget with Dojo
ExtJS: Writing Ext 2 Plugins

Dojo, MooTools, jQuery, prototype: Creating an AJAX Rating Widget

The first 3 losers

• MooTools:
• extends many of js built-in objects
• lack of namespace
• Prototype:
• extends js built-in objects
• no namespacing
• qooxdoo
• not mature enough (still beta)

The final 4 contenders

• jQuery
• blooming community
• beautiful and concise language
• lightweight
• Dojo
• most powerful
• Ext JS
• possibility to combine with JUI or jQuery
• YUI
• modular
• docmentation
• CSS framework included

Our Winner

The JS framework we'll use and support in Kauri will be jQuery.