To get the most out of this book, you'll need to have an understanding of HTML and how to create a static web page. You don't need to have any programming experience.

This book will also suit you if you have some programming experience already and would like to turn your hand to web programming. You will know a fair amount about computing concepts, but maybe not as much about web technologies.

Alternatively, you may have a design background and know relatively little about the web and computing concepts. For you, JavaScript will be a cheap and relatively easy introduction to the world of programming and web application development.

Whoever you are, we hope that this book lives up to your expectations.

You'll begin by looking at exactly what JavaScript is, and taking your first steps with the underlying language and syntax. You'll learn all the fundamental programming concepts, including data and data types, and structuring your code to make decisions in your programs or to loop over the same piece of code many times.

Once you're comfortable with the basics, you'll move on to one of the key ideas in JavaScript — the object. You'll learn how to take advantage of the objects that are native to the JavaScript language, such as dates and strings, and find out how these objects enable you to manage complex data and simplify your programs. Next, you'll see how you can use JavaScript to manipulate objects made available to you in the browser, such as forms, windows, and other controls. Using this knowledge, you can start to create truly professional-looking applications that enable you to interact with the user.

Long pieces of code are very hard to get right every time — even for the experienced programmer — and JavaScript code is no exception. You look at common syntax and logical errors, how you can spot them, and how to use the JavaScript debuggers for Firefox, Internet Explorer, Safari/Chrome, and Opera to aid you with this task. Also, you need to examine how to handle the errors that slip through the net, and ensure that these do not detract from the experience of the end user of your application.

From here, you'll move on to more advanced topics, such as using cookies and jazzing up your web pages with dynamic HTML and XML. Finally, you'll be looking at a relatively new and exciting technology: Ajax. This allows your JavaScript in a HTML page to communicate directly with a server, and useful for, say, looking up information on a database sitting on your server. If you have the Google toolbar you'll have seen something like this in action already. When you type a search word in the Google toolbar, it comes up with suggestions, which it gets via the Google search database.

Finally, you'll explore some of the time saving JavaScript frameworks such as jQuery, Prototype, and MooTools and seeing how they work and how they can help you create sophisticated JavaScript powered applications.

All the new concepts introduced in this book will be illustrated with practical examples, which enable you to experiment with JavaScript and build on the theory that you have just learned.

You'll find four appendixes at the end of the book. Appendix A provides solutions to the exercises included at the end of most chapters throughout the book. The remaining appendixes contain the reference material that your authors hope you find useful and informational. Appendix B contains the JavaScript language's core reference. Appendix C contains a complete W3C DOM Core reference — as well as information on the HTML DOM and DOM Level 2 Event model. Appendix D contains the decimal and hexadecimal character codes for the Latin-1 character set.

Because JavaScript is a text-based technology, all you really need to create documents containing JavaScript is Notepad (or your equivalent text editor).

Also, in order to try out the code in this book, you will need a web browser that supports a modern version of JavaScript. Ideally, this means Internet Explorer 8 or later and Firefox 3 or later. The book has been extensively tested with these two browsers. However, the code should work in most modern web browsers, although some of the code in later chapters, where you examine dynamic HTML and scripting the DOM, is specific to particular browsers; but the majority of the code presented is cross-browser. Where there are exceptions, they will be clearly noted.

To help you get the most from the text and keep track of what's happening, we've used a number of conventions throughout the book.

Important code in code examples is highlighted with a gray background.
The gray highlighting is not used for code that's less important in the present
context, or that has been shown before.

As you work through the examples in this book, you may choose either to type in all the code manually or to use the source-code files that accompany the book. All of the source code used in this book is available for download at www.wrox.com. Once at the site, simply locate the book's title (either by using the Search box or by using one of the title lists) and click the Download Code link on the book's detail page to obtain all the source code for the book.

Once you download the code, just decompress it with your favorite compression tool. Alternately, you can go to the main Wrox code download page at www.wrox.com/dynamic/books/download.aspx to see the code available for this book and all other Wrox books.

We make every effort to ensure that there are no errors in the text or in the code. However, no one is perfect, and mistakes do occur. If you find an error in one of our books, like a spelling mistake or faulty piece of code, we would be very grateful for your feedback. By sending in errata, you may save another reader hours of frustration, and at the same time you will be helping us provide even higher-quality information.

To find the errata page for this book, go to www.wrox.com and locate the title using the Search box or one of the title lists. Then, on the book details page, click the Book Errata link. On this page you can view all errata that have been submitted for this book and posted by Wrox editors. A complete book list, including links to each book's errata, is also available at www.wrox.com/misc-pages/booklist.shtml.

If you don't spot "your" error on the Book Errata page, go to www.wrox.com/contact/techsupport.shtml and complete the form there to send us the error you have found. We'll check the information and, if appropriate, post a message to the book's errata page and fix the problem in subsequent editions of the book.

For author and peer discussion, join the P2P forums at p2p.wrox.com. The forums are a web-based system on which you can post messages relating to Wrox books and related technologies and interact with other readers and technology users. The forums offer a subscription feature to e-mail you topics of interest of your choosing when new posts are made to the forums. Wrox authors, editors, other industry experts, and your fellow readers are present on these forums.

At http://p2p.wrox.com you will find a number of different forums that will help you not only as you read this book, but also as you develop your own applications. To join the forums, just follow these steps:

Once you join, you can post new messages and respond to messages other users post. You can read messages at any time on the Web. If you would like to have new messages from a particular forum e-mailed to you, click the Subscribe to this Forum icon by the forum name in the forum listing.

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