Tom Negrino - JavaScript: Visual QuickStart Guide (8th Edition)

Visual QuickStart Guide

Eighth Edition

Tom Negrino
Dori Smith

Visual QuickStart Guide
JavaScript, Eighth Edition
Tom Negrino and Dori Smith

Peachpit Press
1249 Eighth Street
Berkeley, CA 94710
(510) 524-2178
(510) 524-2221 (fax)

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Peachpit Press is a division of Pearson Education

Copyright 2012 by Tom Negrino and Dori Smith

Editor: Nancy Peterson
Production Editor: Tracey Croom
Copyeditor: Scout Festa
Compositor: Danielle Foster
Indexer: Emily Glossbrenner
Cover Design: RHDG / Riezebos Holzbaur Design Group, Peachpit Press
Interior Design: Peachpit Press
Logo Design: MINE www.minesf.com

Notice of rights

All rights reserved. No part of this book may be reproduced or transmitted in any form by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. For information on getting permission for reprints and excerpts, contact

Notice of liability

The information in this book is distributed on an As is basis, without warranty. While every precaution has been taken in the preparation of the book, neither the authors nor Peachpit Press, shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the instructions contained in this book or by the computer software and hardware products described in it.

Trademarks

Visual QuickStart Guide is a registered trademark of Peachpit Press, a division of Pearson Education. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and Peachpit Press was aware of a trademark claim, the designations appear as requested by the owner of the trademark. All other product names and services identified throughout this book are used in editorial fashion only and for the benefit of such companies with no intention of infringement of the trademark. No such use, or the use of any trade name, is intended to convey endorsement or other affiliation with this book.

ISBN 13: 978-0-321-77297-8
ISBN 10: 0-321-77297-0

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Printed in the United States of America

To the memory of Bill Horwitz and Dorothy Negrino, because they loved learning.

Big thanks to our editor Nancy Peterson; her expert touch, serenity, and compassion made this edition a pleasant one to create.

Thanks to Tracey Croom for her excellent production work and to Scout Festa for her skillful copyediting.

Our heartfelt thanks to Danielle Foster, the books compositor, who laid out the book and pulled off the job with grace and aplomb, and to the indexer, Emily Glossbrenner, who should be thanked for doing a thankless job.

Were grateful to Peachpits Nancy Ruenzel and Nancy Davis for their support.

Wed like to express our special thanks to all of the high school, college, and university instructors who chose to use the previous editions of this book as a textbook for their classes.

Between the time we signed the contract for this book and when we began working on it, Dori was offered her dream job at Stack Exchange (http://www.stackexchange.com). She could not have worked two jobs and still maintained a semblance of sanity without a great deal of help from others, for which she is truly grateful. In particular:

Thanks to all the great folks at Stack: Joel Spolsky, Jeff Atwood, Robert Cartaino, Rebecca Chernoff, and Josh Heyer, among otherswho gave their time and patience to help me stay employed while finishing this book.

Thanks also to the amazingly patient women at PeachpitIve worked with you for 14 years, and Im still in awe of what youre able to create.

And in particular, I must thank my co-author, Tom Negrino, who did much more than his share of the load on this edition, and who postponed his (and my) tenth wedding anniversary celebration until the book was complete.

Welcome to JavaScript! Using this easy-to-learn programming language, youll be able to add pizzazz to your Web pages and make them more useful for you and for your sites visitors. Weve written this book as a painless introduction to JavaScript, so you dont have to be a geek or a nerd to write a script. Pocket protectors will not be necessary at any time. As a friend of ours says, Were geeky, so you dont have to be!

We figure that if youre interested in JavaScript, then youve already got some experience in creating HTML pages and Web sites, and you want to take the next step by adding some interactivity to your sites. We dont assume that you know anything about programming or scripting. We also dont assume that you are an HTML expert (though if you are, thats just fine). We do assume that youve got at least the basics of building Web pages down, and that you have some familiarity with common HTML, such as links, images, and forms.

We include some extra explanation of HTML in sidebars called Just Enough HTML. You wont find these sidebars in every chapter, just the ones where we think youll need a quick reference. Having this information handy means you wont need multiple books or Web pages open just to remember the syntax of a particular HTML attribute.

If you already know something about programming, you should be aware that we dont take the same approach to JavaScript as you might have seen in other books. We dont delve deeply into JavaScripts syntax and structure, and we dont pretend that this book is a comprehensive language reference (though youll find some valuable reference material in . The difference between those books and this one is that instead of getting bogged down in formalism, we concentrate on showing you how to get useful tasks done with JavaScript without a lot of extraneous information.

In previous editions, we added an introduction to Ajax, a technique that uses JavaScript and other common Web technologies to add extra interactivity to Web pages, and to improve the user experience of your Web sites. We covered the basics of Ajax and added some practical examples to allow you to Ajax-ify your sites without getting an advanced degree in Web programming. In this edition, weve added even more examples and techniques, using the jQuery frameworkwhich you can think of as building blocks that allow you to easily add useful features to your sites.

Throughout the book, weve used some devices that should make it easier for you to work both with the book and with JavaScript itself.

In the step-by-step instructions that make up most of the book, weve used a special type style to denote either HTML or JavaScript code, like this: