Product review: Inside open source AJAX toolkits
Some decisions will depend upon the scope of the project. The best choice for adding a few fancy AJAX widgets to a site is often quite different from the best choice for building a full-fledged AJAX Web application. Other decisions may be matters of taste. The best library for an ex-Java programmer may differ from, say, one for a Perl hacker.
[ See "Refining the art of enterprise Web apps" for our review of JackBe Presto and Nexaweb Enterprise Web 2.0 Suite; see also "Top AJAX tools deliver rich GUI goodness" for reviews of Backbase, Bindows, JackBe NQ Suite, and Tibco General Interface. ]
The good news is that there are now more libraries than any sane person can even consider in a lifetime. While we concentrate on the more established kits -- Dojo, Ext, Google Web Toolkit, jQuery, MooTools, Prototype and Scriptaculous, and Yahoo User Interface Library -- there are literally hundreds more that are flourishing. Some are big names that people will feel we were mistaken to exclude, but most live in small niches, such as providing slideshows for pictures downloaded from Flickr. Some are independent, but many of the most popular libraries hold entire constellations of semi-independent projects that use the core library. And there's plenty of cross-fertilization. A good idea or piece of code from one group is often adopted by others.
Many of the open source libraries are best for programmers who need to add a bit of AJAX functionality to a Web page. If you want to add a color chooser, a date chooser, and a touch of form preprocessing to a page, then many open source libraries are great for the job. They are usually collections of tools in different states of development. The library managers have smoothed over any differences and applied a common philosophy to much of the code. You get a unified approach that has been tested in a number of the major browsers.