The book was conceived after the architecture and core design of Palm webOS and the Mojo framework had been completed, but while the team was fully engaged with implementation of the application runtime, the Mojo framework, and while many of the core applications were still in prototype form. As a result, the book has been written at the same time as the software, which makes it fresh but raw information.

The project changed dramatically soon after it began. Originally, I saw my role more as that of an editor. I expected to pull together the engineering and developer documentation and write a heavily annotated reference book that would provide a guided tutorial to webOS and Mojo. After the first chapter, though, it became clear that I would have to write a specific application that would use a significant portion of the API and document my experience. I scaled back the outline from a reference book to more of an application-centered guidebook focused on an RSS reader application called News.

This book is not a comprehensive reference, but more of a guided tutorial. It covers all the basics for creating and building an application and for using UI widgets, storage, and services. It includes specific chapters on building background applications, a huge topic of its own, and on specialty topics of building localized applications and on styling. You will want to augment this book with SDK documentation or other reference material as it becomes available.

You don’t need to be an expert, but you will need some basic knowledge of JavaScript, HTML, and CSS to follow the examples presented here. This book is intended to provide an introduction to webOS and building webOS applications, but should not be used as a guide to writing JavaScript code. In fact, I have to warn you that I wrote my first JavaScript code as part of writing this book and it’s very likely that you will see several examples of not-so-good JavaScript in here.

So please read this book to learn how to write great webOS applications, but look for your JavaScript guidance in other sources such as Douglas Crockford’s outstanding JavaScript: The Good Parts (O’Reilly) or the comprehensive JavaScript: The Definitive Guide by David Flanagan (O’Reilly).