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Tutorials JavaScript Manual of Style Marc Johnson CONTENTS Introduction Chapter 1   What Is JavaScript? The history of JavaScript HTML 1.0 and 2.0 HTML 3.0 and NHTML LiveScript What JavaScript isn't CGI Java Platforms and browsers Chapter 2   What Can You Do with JavaScript? Multipart documents with frames Reloading Part of the Window Creating Interactive Documents More control over user interaction Documents with memory Live documents Scrolling Messages Clocks Countdown Timers Self-Updating Documents Chapter 3   Style Image is everything Content Presentation Protecting your document from rogue users Make Sure Your Functions Are Loaded Validate Input But Surely No One Would Do That! Not All Platforms Are Created Equal, Part 2 Document maintenance Comment, Comment, Comment Consistent Internal Style The last rule Chapter 4   URL Patch The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) Modifying the example for your own use Chapter 5   An Outlined Document The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) Frame in the Outline Make the Document Outline Smarter Modifying the example for your own use Chapter 6   Color Chooser The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) The Form Improving the solution Modifying the example for your own use Chapter 7   Form Validation The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) Improving the solution Modifying the example for your own use Chapter 8   Form Modification The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) Laying Out the Controls Laying Out the Window Adding Functionality to the Controls Putting Everything Together Improving the solution Modifying the example for your own use Chapter 9   Games The scenario The requirements The solution (without JavaScript) The solution (with JavaScript) Improving the solution Modifying the example for your own use AppendixA   ISO Latin-1 Character Set   Appendix B   JavaScript Reserved Words Appendix C   A Review of HTML The basic structure of a Web page Uniform Resource Locators Colors Alignment Clear Netscape-supported HTML elements ADDRESS APPLET AREA B (Boldface) BASE BASEFONT BIG BLINK BLOCKQUOTE BODY BR (Line Break) CAPTION CENTER CITE CODE DD (Definition Description) DIR (Directory) DIV (Division) DL (Definition List) DT (Definition Term) EM (Emphasis) FONT FORM FRAME FRAMESET H1, H2, H3, H4, H5, and H6 (Headings) HEAD HR (Horizontal Rule) HTML I (Italic) IMG (Image) INPUT ISINDEX (Is Indexed) KBD (Keyboard) LI (List Item) LINK MAP MENU META (Document Meta-Information) NOBR (No Break) NOFRAME OL (Ordered List) OPTION P (Paragraph) PARAM (Applet Parameter) PRE (Preformatted Text) SAMP (Literal Characters) SCRIPT SELECT SMALL STRIKE STRONG (Strong Emphasis) SUB (Subscript) SUP (Superscript) TABLE TD (Table Data) and TH (Table Header) TEXTAREA TITLE TR (Table Row) TT (Teletype) UL (Unordered List) VAR (Variable) WBR (Word Break) Appendix D   JavaScript Operators Operators Addition Operator Assignment Operator Bitwise AND Operator Bitwise Exclusive-Or (XOR) Operator Bitwise OR Operator Bitwise Negate Operator Concatenation Operator Conditional Operator Division Operator Equality Operator Greater Than Operator Greater Than or Equal Operator Inequality Operator Less Than Operator Less Than or Equal Operator Logical AND Operator Logical NOT Operator Logical OR Operator Modulo Operator Multiplication Operator Negation Operator Post-Decrement Operator Post-Increment Operator Pre-Decrement Operator Pre-Increment Operator Shift Left Operator Sign-Propagating Shift Right Operator Shorthand Assignment Operator Subtraction Operator Zero-Fill Shift Right Operator Order of precedence Appendix E   Built-in Objects and Functions Built-in objects The anchors Array The button Object The checkbox Object The Date Object The document Object The elements Array The form Object The forms Array The frame Object The frames Array The hidden Object The history Object The link Object The links Array The location Object The Math Object The navigator Object The options Array The password Object The radio Object The reset Object The select Object The string Object The submit Object The text Object The textarea Object The window Object Built-in functions Appendix F   Online Resources   Credits   HTML conversion by :     M/s. LeafWriters (India) Pvt. Ltd.     Website : http://leaf.stpn.soft.net     e-mail : leafwriters@leaf.stpn.soft.net     Acquisitions Editor Suzanne Anthony Coordinating Editor Kelly Green Editor Deborah Craig Technical Reviewer Luke Cassady-Dorion Project Coordinator Barbara Dahl Cover Illustration Regan Honda Cover Design Regan Honda and Megan Gandt Book Design Gary Suen Word Processing Howard Blechman Page Layout Janet Piercy Indexer Valerie Robbins   Copyright © 1996 by Macmillan Computer Publishing USA. All rights reserved. PART OF A CONTINUING SERIES All other product names and services identified throughout this book are trademarks or registered trademarks of their respective companies. They are used throughout this book in editorial fashion only and for the benefit of such companies. No such uses, or the use of any trade name, is intended to convey endorsement or other affiliation with the book. No part of this publication may be reproduced in any form, or stored in a database or retrieval system, or transmitted or distributed in any form by any means, electronic, mechanical photocopying, recording, or otherwise, without the prior written permission of Macmillan Computer Publishing USA, except as permitted by the Copyright Act of 1976, and except that program listings may be entered, stored, and executed in a computer system. THE INFORMATION AND MATERIAL CONTAINED IN THIS BOOK ARE PROVIDED "AS IS," WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTY CONCERNING THE ACCURACY, ADEQUACY, OR COMPLETENESS OF SUCH INFORMATION OR MATERIAL OR THE RESULTS TO BE OBTAINED FROM USING SUCH INFORMATION OR MATERIAL. NEITHER MACMILLAN COMPUTER PUBLISHING USA NOR THE AUTHOR SHALL BE RESPONSIBLE FOR ANY CLAIMS ATTRIBUTABLE TO ERRORS, OMISSIONS, OR OTHER INACCURACIES IN THE INFORMATION OR MATERIAL CONTAINED IN THIS BOOK, AND IN NO EVENT SHALL MACMILLAN COMPUTER PUBLISHING USA OR THE AUTHOR BE LIABLE FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF SUCH INFORMATION OR MATERIAL. ISBN 1-56276-423-3     Acknowledgments I thank the superb people I worked with at Ziff-Davis-Stacy Hiquet, Suzanne Anthony, Kelly Green, and Barbara Dahl. I thank my incredible editors, Deborah Craig and Luke Cassady-Dorion, without whom this book never would have made it into your hands. I thank my colleagues at Fujitsu Network Switching, who put up with my demented ramblings about the wonders of JavaScript. I thank Chelsea and Trevor for once more putting up with a daddy who never seems to get enough sleep and who is constantly working on the book-again. I thank Joan for putting up with my schedule, and for getting the ball rolling on yet another book, even though she knew what that entailed and the sacrifices she'd have to make-been there, done that, and did it again anyway. Finally, I thank the Lord for this experience, and I thank the woman who taught me to thank Him, even when I don't understand why-Martha Ilene Larson Whitaker. I dedicate this book to her memory.     Introduction This is a book about writing exciting Web pages with JavaScript. Before JavaScript or its ancestor, LiveScript, Web pages were written in HTML. The pages could be very sophisticated in their layout, but they just sat there. JavaScript can make your Web pages come alive. Your Web pages can now be dynamic, changing before the user's eyes. JavaScript can make your Web pages both more interesting and more fun. JavaScript isn't very difficult to learn. I myself picked up the basics in a matter of hours. You can, too. You don't need to read this book cover to cover, and you don't have to read the chapters in any particular order. Skip around, read what seems interesting, and write some code. It's the best way to learn. You will need a copy of Netscape Navigator, preferably version 2.01 or later, but that's all. I use WebMania! to write some of my code, because it takes care of a lot of the details that I might forget, but all you really need is a simple ASCII text editor-vi, emacs, Notepad, whatever. This book is divided into three parts. The first part includes three chapters. Chapter 1is a quick introduction to JavaScript that describes what it is and where it came from. Chapter 2explains what JavaScript is good for, outlining what you can do with it. Chapter 3lets me get up on my soapbox and do a little preaching about what makes a good Web page, what makes a bad Web page, and what you can do to keep your pages on the good list. The second section consists of six chapters, all of which contain a complete JavaScript Web page. Each chapter introduces a problem, demonstrates how you might solve it without JavaScript, and then shows how you can craft a much better solution with JavaScript. These chapters all conclude with some thoughts on how you can enhance the solution and how you can adapt the techniques to creating your own Web pages with JavaScript. In every chapter, the JavaScript code is discussed in depth, function by function. No mysteries; there's no one behind the curtain. If you don't understand something about the code, write me at marcj@nando.net. I'll be glad to answer your questions! Finally, the third section contains six appendices, chock full of useful reference material: the character set, reserved words, a review of HTML, the JavaScript operators, JavaScript's built-in objects and functions, and online resources. Again, if there's something I missed, write me. I want to help. This book was written on a nameless 486-based desktop system lovingly assembled by Computer Options of Raleigh, North Carolina, and on a Pentium-based Samsung notebook, using Microsoft Word for Windows 6.0 under Windows 3.1 (the desktop) and Windows 95 (the notebook). The Web pages created were tested on both platforms, as well as on a Sun Microsystems Sparc-10 running Solaris 2.4 and on the desktop system under Linux 1.2.1. Luke Cassady-Dorion, my excellent technical editor, also ran them on his Macintosh. The Web pages were written with WebMania! 1.5. Screen shots were taken with Collage Complete 1.0, and enhanced with Paint Shop Pro 3.12. My Web space provider is Hurricane Electric (he.net; my home page is http://www.he.net/~marcj/index.phpl), and the Web pages were loaded onto their server for live testing. All of this was accomplished through my Internet service provider, nando.net. I had a lot of fun writing this book, and I hope it proves to be a useful addition to your library.

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