by Dan Webb

Prototype is an object oriented JavaScript library (written by Sam Stephenson and friends) that makes JavaScript fun. So it says on the site, anyway. Those of you who are familiar with the open source community's latest and greatest application framework, Rails, may recognise Prototype as it actually forms the backbone of Rails' JavaScript helper. However, Prototype can be used independently of Rails to aid the coding of many JavaScript doodads and Web 2.0 thingy wangles.

Personally, I think the jury's out on the whole 'fun' JavaScript thing, but nevertheless Prototype is a really well executed JavaScript library which, although the situation has been improving of late, has had notoriously sparse documentation. This article provides a whirlwind tour of the whole library. It aims to give you enough examples and resources to get started using Prototype in your DOM scripting projects.

First, we'll examine the basic building blocks of Prototype: its $ functions, its additions to the String, Number, Array and Function objects, its form handling capabilities and its DOM functions. Then, we'll move on to look at Prototype's well-known AJAX helpers. Finally, we'll finish with a brief discussion of other interesting projects that are based on it.

I'd like to note that the current stable version of Prototype at time of writing is 1.4.0. I have a feeling that the library will change quite quickly in response to Rails' lightning-quick development cycle, so things will change. The final boring note is that at this time Prototype only supports the newer browsers -- as you might expect of a DOM and XMLHttpRequest based library. See the Prototype site for details of browser support.