About You

Client-side scripting and DHTML are such broad and deep subjects that virtually every reader coming to this book will have different experience levels, expectations, and perhaps, fears. No book could hope to anticipate every possible question from someone wishing to use these technologies in their web pages. Therefore, this book makes some assumptions about readers at various stages of their experience:

• You have at least rudimentary knowledge of client-side JavaScript concepts. You know how to put scripts into a web page — where <script> tags go as well as how to link an external .js file into the current page. You also know what variables, strings, numbers, Booleans, arrays, and objects are—even if you don't necessarily remember the precise way they're used with the JavaScript language. This book is not a tutorial, but you can learn a lot from reading the introductions to each chapter and the discussions following each solution.

• You may be a casual scripter, who wants to put a bit of intelligence into a web page for some project or other. You don't use the language or object model every day, so you need a refresher about even some simple things, such as the correct syntax for creating an array or pre-loading images for fast image rollover effects.

• While surfing the Web, you may have encountered some scripted DHTML effect that you'd like to implement or adapt for your own pages, but either you can't decipher the code you see or you want to "roll your own" version to avoid copyright problems with the code's original owner. If the effect or technique you've seen is fairly popular, this cookbook probably has a recipe for it. You can use these recipes as they are or modify them to fit your designs. There are no royalties or copyrights to worry about, as long as you don't offer these recipes to others as part of a collection of scripts. Of course, if you wish to acknowledge this book in your source code comments, that would be great!

• You may be an experienced web developer who has probed gingerly, if at all, into client-side scripting. The horror stories of yore about browser incompatibilities have kept your focus entirely on server-side programming. But now that so many mainstream sites are using client-side scripting to improve the user experience, you are ready to take another look at what is out there.

• At the far end of the spectrum, you may be an experienced client-side DHTML developer in search of new ideas and techniques. For instance, you may have developed exclusively for the Internet Explorer browser on the Windows platform, but you wish to gravitate toward standards-compatible syntax for future coding.

Virtually every reader will find that some recipes in this book are too simple and others are too complex for their experience level. I hope the more difficult ones challenge you to learn more and improve your skills. Even if you think you know it all, be sure to check the discussions of the easier recipes for tips and insights that may be new to you.