The Yahoo! User Interface Library (affectionately known as the YUI library) is a free resource provided by Yahoo! for web developers. It's a collection of utilities that enable developers to build cross-browser web applications quickly and easily.

Before coming across this book I had never even heard of the YUI library and I was amazed by how helpful it can be for web developers. The YUI library's "plug and play" utilities allow developers with basic JavaScript knowledge to implement effects that would otherwise take a JavaScript master days to build. What's more, the utilities are designed to work seamlessly with all of what Yahoo! calls the grade-A browsers: Internet Explorer, Firefox, Opera and Safari.

I'd highly recommend all web developers become familiar with the YUI library, and the book Learning the Yahoo! User Interface Library, written by Dan Wellman, is an excellent place to start. The book assumes familiarity with JavaScript, HTML and CSS, and I would agree that some knowledge in these areas is required to make the most of the book's information. I would class myself as an "advanced beginner" in JavaScript and I had just enough understanding to follow along.

The author begins by describing the YUI library and its core components: utilities, controls and CSS files. He walks the reader through installation options and presents examples of YUI integration – demonstrating how a bit of simple code combined with the YUI tools can allow a developer to build an interactive calendar on her website.

He goes on to describe each of the YUI library's offerings; CSS tools, DOM event handling, the AJAX Connection Manager, animation tools, button controls and tree builders, navigation and menu builders, container utilities, drag-and-drop tools, and debugging options. Chapter Three, DOM manipulation, was particularly useful for me since I didn't know much about DOM. Mr. Wellman begins by defining DOM (Document Object Model) and explaining why it's useful for developers (it gives you access to the structure of a document, which allows you to manipulate elements of that document). He then shows how YUI tools make DOM manipulation far simpler.

Learning the Yahoo! User Interface Library is a great guide to the YUI library. Mr. Wellman provides plenty of specifics, including detailed code samples. You also have access to a zip file on the publisher's web site that provides copies of all the book's code samples and images required for those samples.

I did notice a few typos throughout the book. Most of them were harmless, but one that stuck out was the fact that in several code samples 'var' (the JavaScript statement that's used to declare a variable) was typed with a capital 'V.' For the uninitiated, JavaScript is case sensitive so 'Var' will NOT work and your program will fail. Since I typed the code samples directly from the examples in the book, I spent a frustrating half hour trying to figure out why the first program wouldn't run before I noticed this error.

Overall, I'd give Learning the Yahoo! User Interface Library a solid 4 out of 5. The YUI is a fantastic tool for developers, and this particular book is a good choice for any developer getting started with the YUI library – just watch out for those 'Vars'!

Learning the Yahoo! User Interface library