Product review: Inside open source AJAX toolkits
Prototype 1.6 (and Scriptaculous 1.8.1)
Support: Mailing list and IRC
Nutshell: A quick, lightweight mechanism for manipulating the DOM and making a few calls to a Web service
These two projects are smaller, simpler approaches to manipulating a Web page with few of the bigger aspirations of the other major AJAX projects, but they are still very popular. Prototype is a relatively simple and tiny layer that offers both shorthand versions for popular functions and a good amount of cross-browser abstraction. Scriptaculous is a set of special effects and simple widgets built on top of Prototype.
Scriptaculous continues to offer some of the more sophisticated effects for making divs puff, shake, pulsate, shrink, fold, or about a dozen other combinations. While there has not been a noticeable improvement in this collection over the last year, Scriptaculous continues to be one of the simplest and best ways to add the kind of eye candy that bosses seem to love on demonstration day. The effects can be combined to act in concert with little extra work.
The Scriptaculous library is not the only collection built on top of Prototype. Rico, for instance, offers a nice live grid and several other features. A number of slideshow applications, such as Carousel, are also available. Many of the smaller, independent widgets are often built on top of Prototype.
This pan-AJAX popularity, however, doesn't mean that all of the widgets operate well with each other. Just because two libraries from different programmers use the $() function doesn't mean that the approach to structuring the DOM tree or passing events is going to work well together.
For the near future, Prototype will continue to be very popular because its lightweight approach offers what most AJAX developers need: a few easy handles for tweaking a few DOM objects and a simple way to issue a few XMLHttpRequest calls. (One survey of popular code on AjaxPatterns.org called it the most popular library of all.) But this may change if full Web applications become more popular and AJAX developers start embracing the kind of complexity that can be found in many client applications.