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Biblia javascript

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Manual completo para empezar con javascript

Manual completo para empezar con javascript

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    • Turn in: .75 Board: 7.0625 .4375 VISIBLE SPINE = 2.375 .4375 Board: 7.0625 Turn in: .75 The Ultimate Guide to JavaScript for Professionals GOLD EDITION G O L D E D I T I O N Featuring 15 bonus chapters with expanded coverage of data validation, debugging, plug-ins, security, and more, “I highly recommend Danny Goodman’s Advance your JavaScript JavaScript Bible.” JavaScript plus nine chapters on ready-to-use applications, this monumental reference is truly the most comprehensive and JavaScript skills with the most —Brendan Eich, creator of JavaScript useful guide to JavaScript available today. Writing with his trademark clarity and verve, leading JavaScript comprehensive resource authority Danny Goodman covers everything from Cascading Style Sheets and Document Object Models to available XML data — and gives you all the tools you need to harness the full power of client-side JavaScript. Conquer high-end Encyclopedic coverage of “I continue to use the book [JavaScript Bible] on a daily basis and would be lost without it.” scripting challenges using JavaScript and DOMs —Mike Warner, Founder, Oak Place Publications the latest techniques • Master JavaScript and DOM concepts with Danny’s “Whether you are a professional or a beginner, exclusive interactive workbench: The Evaluator Optimize scripts for this is a great book to get.” —Brant Mutch, Web Application Developer, Internet Explorer 5.5 • Learn state-of-the-art debugging and tracing tricks Wells Fargo Card Services, Inc. and Netscape Navigator 6 • Apply the latest JavaScript 1.5 exception handling and custom object techniques • Implement cross-browser Dynamic HTML applications for MSIE 5.5 and Navigator 6 Turn plain Features 15 pages into bonus chapters The Definitive • Embed a universal sound plug-in controller in your interactive JavaScript Guide pages applications — Over 175,000 • Develop deployment strategies that best suit Copies in Print JavaScript your content goals and target audience ® CD-ROM includes: ® • A searchable e-version of the book • Nearly 300 ready-to-run scripts from the book • Printable version of the JavaScript and Browser GOODMAN Object Quick Reference • Plus the full version of WebSpice Objects, a www.hungr yminds.com Bible demo of BBEdit, and TextPad shareware Bible System Requirements: $ 69.99 USA Reader Level: Shelving Category: PC running Windows 95 or later, Windows $104.99 Canada Beginning to Advanced Web Development/JavaScript NT 4 or later; Power Macintosh running £ 55.99 UK incl. VAT Hundreds of Example System 7.6 or later. See Appendix E for Scripts on CD-ROM! details and complete system requirements. ISBN 0-7645-4718-6 CD-ROM *85 5 -ADAG e ,!7IA7G4-fehbi !:p;Q;T;t;t INSIDE! Nearly 300 Ready-to-Run Example Scripts and More Danny Goodman JavaScript pioneer and Consultant on CD-ROM! With a foreword by Brendan Eich, creator of JavaScript
    • Praise for Danny Goodman’s JavaScript Bible “JavaScript Bible is the definitive resource in JavaScript programming. I am never more than three feet from my copy.” — Steve Reich, CEO, PageCoders “This book is a must-have for any Web developer or programmer.” — Thoma Lile, President, Kanis Technologies, Inc. “Outstanding book. I would recommend this book to anyone interested in learning to develop advanced Web sites. Mr. Goodman did an excellent job of organizing this book and writing it so that even a beginning programmer can understand it.” — Jason Hensley, Director of Internet Services, NetVoice, Inc. “Goodman is always great at delivering clear and concise technical books!” — Dwayne King, Chief Technology Officer, White Horse “JavaScript Bible is well worth the money spent!” — Yen C.Y. Leong, IT Director, Moo Mooltimedia, a member of SmartTransact Group “A must-have book for any Internet developer.” — Uri Fremder, Senior Consultant, TopTier Software “I love this book! I use it all the time, and it always delivers. It’s the only JavaScript book I use!” — Jason Badger, Web Developer “Whether you are a professional or a beginner, this is a great book to get.” — Brant Mutch, Web Application Developer, Wells Fargo Card Services, Inc. “I never thought I’d ever teach programming before reading your book [JavaScript Bible]. It’s so simple to use — the Programming Fundamentals section brought it all back! Thank you for such a wonderful book, and for breaking through my program- ming block!” — Susan Sann Mahon, Certified Lotus Instructor, TechNet Training “I continue to get so much benefit from JavaScript Bible. What an amazing book! Danny Goodman is the greatest!” — Patrick Moss “Danny Goodman is very good at leading the reader into the subject. JavaScript Bible has everything we could possibly need.” — Philip Gurdon
    • “An excellent book that builds solidly from whatever level the reader is at. A book thatis both witty and educational.” — Dave Vane“I continue to use the book on a daily basis and would be lost without it.” — Mike Warner, Founder, Oak Place Productions“JavaScript Bible is by far the best JavaScript resource I’ve ever seen (and I’ve seenquite a few).” — Robert J. Mirro, Independent Consultant, RJM Consulting
    • JavaScript Bible, ® Gold Edition
    • JavaScript Bible, ® Gold Edition Danny Goodman With a foreword by Brendan Eich, creator of JavaScriptBest-Selling Books • Digital Downloads • e-Books • Answer Networks • e-Newsletters • Branded Web Sites • e-Learning Indianapolis, IN ✦ Cleveland, OH ✦ New York, NY
    • JavaScript® Bible, Gold Edition Contemporanea de Ediciones for Venezuela; byPublished by Express Computer Distributors for the Caribbean andHungry Minds, Inc. West Indies; by Micronesia Media Distributor, Inc. for909 Third Avenue Micronesia; by Chips Computadoras S.A. de C.V. forNew York, NY 10022 Mexico; by Editorial Norma de Panama S.A. forwww.hungryminds.com Panama; by American Bookshops for Finland.Copyright © 2001 Danny Goodman. All rights For general information on Hungry Minds’ productsreserved. No part of this book, including interior and services please contact our Customer Caredesign, cover design, and icons, may be reproduced department; within the U.S. at 800-762-2974, outsideor transmitted in any form, by any means (electronic, the U.S. at 317-572-3993 or fax 317-572-4002.photocopying, recording, or otherwise) without the For sales inquiries and resellers information,prior written permission of the publisher. including discounts, premium and bulk quantity salesLibrary of Congress Control Number: 2001090713 and foreign language translations please contact our Customer Care department at 800-434-3422, faxISBN: 0-7645-4718-6 317-572-4002 or write to Hungry Minds, Inc., Attn:Printed in the United States of America Customer Care department, 10475 Crosspoint10 9 8 7 6 5 4 3 2 1 Boulevard, Indianapolis, IN 46256.1P/RV/QW/QR/IN For information on licensing foreign or domesticDistributed in the United States by Hungry Minds, Inc. rights, please contact our Sub-Rights Customer CareDistributed by CDG Books Canada Inc. for Canada; by department at 212-884-5000.Transworld Publishers Limited in the United For information on using Hungry Minds’ productsKingdom; by IDG Norge Books for Norway; by IDG and services in the classroom or for orderingSweden Books for Sweden; by IDG Books Australia examination copies, please contact our EducationalPublishing Corporation Pty. Ltd. for Australia and Sales department at 800-434-2086 or fax 317-572-4005.New Zealand; by TransQuest Publishers Pte Ltd. for For press review copies, author interviews, or otherSingapore, Malaysia, Thailand, Indonesia, and Hong publicity information, please contact our PublicKong; by Gotop Information Inc. for Taiwan; by ICG Relations department at 317-572-3168 or faxMuse, Inc. for Japan; by Intersoft for South Africa; by 317-572-4168.Eyrolles for France; by International Thomson For authorization to photocopy items for corporate,Publishing for Germany, Austria, and Switzerland; by personal, or educational use, please contactDistribuidora Cuspide for Argentina; by LR Copyright Clearance Center, 222 Rosewood Drive,International for Brazil; by Galileo Libros for Chile; by Danvers, MA 01923, or fax 978-750-4470.Ediciones ZETA S.C.R. Ltda. for Peru; by WS ComputerPublishing Corporation, Inc., for the Philippines; byLIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND AUTHOR HAVE USED THEIRBEST EFFORTS IN PREPARING THIS BOOK. THE PUBLISHER AND AUTHOR MAKE NOREPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THECONTENTS OF THIS BOOK AND SPECIFICALLY DISCLAIM ANY IMPLIED WARRANTIES OFMERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. THERE ARE NO WARRANTIES WHICHEXTEND BEYOND THE DESCRIPTIONS CONTAINED IN THIS PARAGRAPH. NO WARRANTY MAY BECREATED OR EXTENDED BY SALES REPRESENTATIVES OR WRITTEN SALES MATERIALS. THEACCURACY AND COMPLETENESS OF THE INFORMATION PROVIDED HEREIN AND THE OPINIONSSTATED HEREIN ARE NOT GUARANTEED OR WARRANTED TO PRODUCE ANY PARTICULAR RESULTS,AND THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR EVERYINDIVIDUAL. NEITHER THE PUBLISHER NOR AUTHOR SHALL BE LIABLE FOR ANY LOSS OF PROFIT ORANY OTHER COMMERCIAL DAMAGES, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL,CONSEQUENTIAL, OR OTHER DAMAGES.Trademarks: JavaScript is a registered trademark or trademark of Sun Microsystems, Inc. All othertrademarks are property of their respective owners. Hungry Minds, Inc. is not associated with any productor vendor mentioned in this book. is a trademark of Hungry Minds, Inc.
    • About the Author Danny Goodman is the author of numerous critically acclaimed and best-selling books, including The Complete HyperCard Handbook, Danny Goodman’s AppleScript Handbook, and Dynamic HTML: The Definitive Reference. He is a renowned authority and expert teacher of computer scripting languages and is widely known for his “JavaScript Apostle” articles at Netscape’s ViewSource online developer newsletter. His writing style and pedagogy continue to earn praise from readers and teachers around the world. To help keep his finger on the pulse of real-world programming challenges, Goodman frequently lends his touch as consulting programmer and designer to leading-edge World Wide Web and intranet sites from his home base in the San Francisco area.
    • Credits Acquisitions Editor Quality Control Technicians Debra Williams Cauley Laura Albert Joel Draper Project Editor Andy Hollandbeck Neil Romanosky Susan Moritz Technical Editor Permissions Editor David Wall Laura Moss Copy Editors Media Development Specialist Jerelind Charles Greg Stephens Victoria Lee O’Malley Media Development Coordinator Proof Editor Marisa Pearman Cordelia Heaney Book Designer Editorial Manager Kurt Krames Colleen Totz Proofreading Project Coordinators TECHBOOKS Production Services Cindy Phipps Regina Snyder Indexer Johnna VanHoose Dinse Graphics and Production Specialists Sean Decker Cover Illustrator John Greenough Kate Shaw LeAndra Johnson Stephanie Johnson Gabriele McCann Jill Piscitelli Heather Pope Ron Terry Erin Zeltner
    • Foreword A s JavaScript’s creator, I would like to say a few words about where JavaScript has been, where it is going, and how the book you’re holding will help you to make the most of the language. JavaScript was born out of a desire to let HTML authors write scripts directly in their documents. This may seem obvious now, but in the spring of 1995 it was novel and more than a little at odds with both the conventional wisdom (that HTML should describe static document structure only) and the Next Big Thing (Java applets, which were hyped as the one true way to enliven and extend Web pages). Once I got past these contentions, JavaScript quickly shaped up along the following lines: ✦ “Java-lite” syntax. Although the “natural language” syntax of HyperTalk was fresh in my mind after a friend lent me The Complete HyperCard Handbook by some fellow named Goodman, the Next Big Thing weighed heavier, especially in light of another goal: scripting Java applets. If the scripting language resembled Java, then those pro- grammers who made the jump from JavaScript to Java would welcome similarities in syntax. But insisting on Java’s class and type declarations, or on a semicolon after each statement when a line ending would do, was out of the question — scripting for most people is about writing short snippets of code, quickly and without fuss. ✦ Events for HTML elements. Buttons should have onClick event handlers. Documents load and unload from windows, so windows should have onLoad and onUnload handlers. Users and scripts submit forms: thus the onSubmit handler. Although not initially as flexible as HyperCard’s messages (whose handlers inspired the onEvent naming convention), JavaScript events let HTML authors take control of user interaction from remote servers and respond quickly to user gestures and browser actions. With the adoption of the W3C DOM Level 2 event handling recom- mendations, JavaScript in modern browsers has fully flexible control over events. ✦ Objects without classes. The Self programming language proved the notion of prototype-based inheritance. For JavaScript, I wanted a single prototype per object (for simplicity and efficiency), based by default on the function called using the new operator (for consonance with Java). To avoid distinguishing constructors from methods from functions, all functions receive the object naming them as the prop- erty that was called, in the this parameter. Although prototypes didn’t appear until Navigator 3, they were prefigured in Version 2 by quoted text being treated as an object (the String object prototype, to which users could attach methods). ✦ Generated HTML. Embedding JavaScript in HTML gave rise to a thought: Let the script speak HTML, as if the emitted text and markup were loaded in place of the script itself. The possibilities went beyond automating current or last-modified dates, to computing whole trees of tables where all the repeated structure was rolled up in a scripted loop, while the varying contents to be tabulated came in min- imal fashion from JavaScript objects forming a catalog or mini-database.
    • x JavaScript Bible, Gold Edition At first, I thought JavaScript would most often find use in validating input to HTML forms. But before long, I was surprised to see how many Web designers devised compelling applications by way of script-generated HTML and JavaScript objects. It became clear from user demonstration and feedback that Web designers sought to build significant applications quickly and effectively with just a few images, HTML, and JavaScript. Eventually they demanded that the browser support what is now known as “Dynamic HTML” (one fun link: http://www.javascript-games.org/). As legions of Web authors embraced the authoring power of JavaScript, they, in turn, demonstrated the crucial advantages of a scripting environment over old-school application development. Not only were the HTML and JavaScript languages com- paratively easy to use, but development did not require the programming expertise needed to light all pixels and handle all events as in a big, traditional application. The primacy of JavaScript on the Web today vindicates our early belief in the value of a scripting language for HTML authors. By keeping the “pixel-lighting” bar low, HTML with images has made Web designers out of millions of people. By keeping the “event-handling” bar low, JavaScript has helped many thousands of those designers become programmers. Perhaps the ultimate example of Web develop- ment’s convergence with application development is the Mozilla browser, wherein all of the user-interface and even some custom widgets and modular components are implemented entirely using JavaScript, Cascading Style Sheets (CSS), custom XML-based markup languages, and images. JavaScript is also a general language, useful apart from HTML and XML. It has been embedded in servers, authoring tools, browser plug-ins, and other kinds of browsers (for such things as 3D graphical worlds). Its international standard, ECMA-262 (ISO 16262), has advanced to a Third Edition. But compared with languages such as Perl and even Java, it is still relatively young. Work toward a Fourth Edition of the lan- guage, supporting optional types, classes, and versioning facilities, progresses within the ECMA technical committee (see the “JS2” proposal to the ECMA technical committee documented at http://www.mozilla.org/js/language/js20/). It is clear to me that JavaScript would not have survived without a creative, loyal, and patient community of developers; I owe them each a huge debt of thanks. Those developers who took up the beta releases of Navigator 2 and disseminated vital workarounds and feature requests by e-mail and net-news are the language’s godparents. Developer support and feedback continue to make JavaScript the eclectic, rambunctious success it is. The book in your hands compiles thousands of those “developer miles” with the insight of an expert guide and teacher. Danny didn’t know at the time how much inspi- ration I found in his HyperCard book, but it was on my desk throughout the develop- ment of JavaScript in 1995. His energy, compassion, and clear prose helped me keep the goal of “a language for all” in mind. It is enormously gratifying to write the foreword to the Gold edition of this book, which has earned so many “satisfied reader miles.” I highly recommend Danny Goodman’s JavaScript Bible to anyone who wants to learn JavaScript, and especially to those HTML authors who’ve so far written only a few scripts or programs — you’re in for a lifetime of fun on the “scripting road” with a trusty guide at your side. — Brendan Eich The Mozilla Organization (http://www.mozilla.org)
    • Preface F or nearly 20 years, I have written the books I wished had already been written to help me learn or use a new technology. Whenever possible, I like to get in at the very beginning of a new authoring or programming environment, feel the grow- ing pains, and share with readers the solutions to my struggles. This Gold edition of the JavaScript Bible represents knowledge and experience accumulated over five years of daily work in JavaScript and a constant monitoring of newsgroups for ques- tions, problems, and challenges facing scripters at all levels. My goal is to help you avoid the same frustration and head scratching I and others have experienced through multiple generations of scriptable browsers. While previous editions of this book focused on the then-predominant Netscape Navigator browser, the swing of the browser market share pendulum currently favors Microsoft Internet Explorer. At the same time, Netscape has accomplished the admirable task of reinventing its own browser in light of rapidly advancing industry standards. As a result of both of these trends, this massively revised and expanded Gold edition treats both brands of browsers as equals as far as scripters are concerned. You hear my praise and dismay at various scripting features of both browser families. But empowering you to design and write good scripts is my pas- sion, regardless of browser. Therefore, the book contains details about proprietary and standard implementations to equip you to choose the development path that best fits your content’s audience. If you detect any bias of mine throughout this book, it is a desire, where possible, to write scripts that work on as many browsers as possible.Organization and Features of This Edition Because of the greatly expanded range of vocabularies that scripts may use in the latest browser versions, the biggest change to the structure of the book is in the ref- erence portion. In this edition, you find a greater distinction between the document object model and core JavaScript language reference sections. This new division should help those readers who are primarily interested in only the JavaScript lan- guage (for use in other applications) find what they need more quickly. Here are some details about the book’s structure. Part I Part I of the book begins with a chapter that shows how JavaScript compares with Java and discusses its role within the rest of the World Wide Web. The Web browser and scripting world have undergone significant changes since JavaScript first
    • xii JavaScript Bible, Gold Edition arrived on the scene. That’s why Chapter 2 is devoted to addressing challenges fac- ing scripters who must develop applications for both single- and cross-platform browser audiences amid rapidly changing standards efforts. Chapter 3 provides the first foray into JavaScript, where you get to write your first practical script. Part II All of Part II is handed over to a tutorial for newcomers to JavaScript. Nine lessons provide you with a gradual path through browser internals, basic programming skills, and genuine JavaScript scripting. With only a couple of clearly labeled items, the lessons cover scripting topics that apply to all scriptable browsers. Exercises fol- low at the end of each lesson to help reinforce what you just learned and challenge you to use your new knowledge (you’ll find answers to the exercises in Appendix C). The goal of the tutorial is to equip you with sufficient experience to start scripting simple pages right away while making it easier for you to understand the in-depth discussions and examples in the rest of the book. By the end of the final lesson, you’ll know how to script multiple frame environments and even create the mouse- rollover image swapping effect that is popular in a lot of Web pages these days. On the You can find all of the Part II chapters on the CD-ROM that accompanies this CD-ROM book. Part III Part III, the largest section of the book, provides in-depth coverage of the document object models as implemented in browsers from the earliest days to today. In all ref- erence chapters, a compatibility chart indicates the browser version that supports each object and object feature. One chapter in particular, Chapter 15, contains ref- erence material that is shared by most of the remaining chapters of Part III. To help you refer back to Chapter 15 from other chapters, a dark tab along the outside edge of the page shows you at a glance where the chapter is located. Additional naviga- tion aids include guide words at the bottoms of most pages to indicate which object and object feature is covered on the page. Part IV Reference information for the core JavaScript language fills Part IV. As with refer- ence chapters of Part III, the JavaScript chapters display browser compatibility charts for every JavaScript language term. Guide words at the bottoms of pages help you find a particular term quickly. Part V In Part V, I get down to the business of deploying JavaScript. Here are the practical aspects of JavaScript, such as Chapter 43’s coverage of client-side form data valida- tion and Chapter 44’s coverage of blending Java applets and plug-ins into pages.
    • Preface xiiiDebugging scripts is the focus of Chapter 45, with tips on understanding errormessages, building your own debugging tools. Chapter 46 goes into great detailabout security issues for JavaScript-enabled applications. Dynamic HTML in a cross-browser environment is the subject of Chapter 47, while Chapter 48 introduces youto Microsoft’s behaviors mechanism for Windows.The remaining nine chapters consist of full-fledged applications of JavaScript. Theseapplications are designed not necessarily as plug-and-play modules you can put intoyour pages right away. Instead, their goal is to demonstrate many of the conceptsdescribed earlier in the book by way of real-world examples. New for this edition aresome examples based on XML data islands in Internet Explorer for Windows.Part VIFinally, several appendixes at the end of the book provide helpful reference informa-tion. These resources include a JavaScript and Browser Objects Quick Reference inAppendix A, a list of JavaScript reserved words in Appendix B, answers to Part II’stutorial exercises in Appendix C, and Internet resources in Appendix D. In Appendix E,you also find information on using the CD-ROM that comes with this book.CD-ROMThe accompanying CD-ROM contains over 300 ready-to-run HTML documents thatserve as examples of most of the document object model and JavaScript vocabu-lary words in Parts III and IV. You can run these examples with your JavaScript-enabled browser, but be sure to use the index.html page in the listings folder as agateway to running the listings. This page shows you the browsers that are compat-ible with each example listing. I could have provided you with humorous little sam-ple code fragments out of context, but I think that seeing full-fledged HTMLdocuments (simple though they may be) for employing these concepts is impor-tant. I intentionally omitted the script listings from the tutorial part (Part II) of thisbook to encourage you to type the scripts. I believe you learn a lot, even by apinglistings from the book, as you get used to the rhythms of typing scripts in docu-ments. You also find listings from Parts I and V on the CD-ROM.The CD-ROM holds another valuable resource: dozens and dozens of Example sec-tions for Parts III and IV, which are compiled in Appendix F. Many of these sectionsreveal detailed descriptions of HTML listings that illustrate a particular objectmodel or language feature. Even more Example sections invite you to try out anobject model or language feature with the help of an interactive workbench, calledThe Evaluator — a JavaScript Bible exclusive! You see instant results and quicklylearn how the feature works.The Quick Reference from Appendix A is in .pdf format on the CD-ROM for you toprint out and assemble as a handy reference, if desired. Adobe Acrobat Reader isalso included on the CD-ROM so that you can read this .pdf file. Finally, the text ofthe book is in a .pdf file format on the CD-ROM for easy searching.
    • xiv JavaScript Bible, Gold Edition Prerequisites to Learning JavaScript Although this book doesn’t demand that you have a great deal of programming experience behind you, the more Web pages you’ve created with HTML, the easier you will find it to understand how JavaScript interacts with the familiar elements you normally place in your pages. Occasionally, you will need to modify HTML tags to take advantage of scripting. If you are familiar with those tags already, the JavaScript enhancements will be simple to digest. Forms and their elements (text fields, buttons, and selection lists) play an espe- cially important role in much of typical JavaScript work. You should be familiar with these elements and their HTML attributes. Fortunately, you won’t need to know about server scripting or passing information from a form to a server. The focus here is on client-side scripting, which operates independently of the server after the JavaScript-enhanced HTML page is fully loaded into the browser. The basic vocabulary of the current HTML standard should be part of your working knowledge. When we get to using frames, for instance, the focus is on how to script these elements, not on designing pages with them. Microsoft, Netscape, and other online sources provide more detailed explanations of frames. If you’ve never programmed before To someone who learned HTML from a slim guidebook a few years ago, the size of this book must be daunting. JavaScript may not be the easiest language in the world to learn, but believe me, it’s a far cry from having to learn a full programming language, such as Java or C. Unlike developing a full-fledged monolithic application (such as the productivity programs you buy in the stores), JavaScript lets you experiment by writing small snippets of program code to accomplish big things. The JavaScript interpreter built into every scriptable browser does a great deal of the technical work for you. Programming, at its most basic level, consists of nothing more than writing a series of instructions for the computer to follow. We humans follow instructions all the time, even if we don’t realize it. Traveling to a friend’s house is a sequence of small instruc- tions: Go three blocks that way; turn left here; turn right there. Amid these instruc- tions are some decisions that we have to make: If the stoplight is red, then stop; if the light is green, then go; if the light is yellow, then floor it. Occasionally, we must repeat some operations several times (kind of like having to go around the block until a parking space opens up). A computer program not only contains the main sequence of steps, but it also anticipates what decisions or repetitions may be needed to accomplish the program’s goal (such as how to handle the various states of a stop- light or what to do if someone just stole the parking spot you were aiming for). The initial hurdle of learning to program is becoming comfortable with the way a programming language wants its words and numbers organized in these instruc- tions. Such rules are called syntax, the same as in a living language. Because com- puters generally are dumb electronic hulks, they aren’t very forgiving if you don’t
    • Preface xvcommunicate with them in the specific language they understand. When speakingto another human, you can flub a sentence’s syntax and still have a good chance ofthe other person’s understanding you fully. Not so with computer programming lan-guages. If the syntax isn’t perfect (or at least within the language’s range of knowl-edge that it can correct), the computer has the brazenness to tell you that you havemade a syntax error.The best thing you can do is to just chalk up the syntax errors you receive as learn-ing experiences. Even experienced programmers get them. Every syntax error youget — and every resolution of that error made by rewriting the waywardstatement — adds to your knowledge of the language.If you’ve done a little programming beforeProgramming experience in a procedural language, such as BASIC or Pascal, mayalmost be a hindrance rather than a help to learning JavaScript. Although you mayhave an appreciation for precision in syntax, the overall concept of how a programfits into the world is probably radically different from how JavaScript works. Part ofthis has to do with the typical tasks a script performs (carrying out a very specifictask in response to user action within a Web page), but a large part also has to dowith the nature of object-oriented programming.In a typical procedural program, the programmer is responsible for everything thatappears on the screen and everything that happens under the hood. When the pro-gram first runs, a great deal of code is dedicated to setting up the visual environ-ment. Perhaps the screen contains several text entry fields or clickable buttons. Todetermine which button a user clicks, the program examines the coordinates of theclick and compares those coordinates against a list of all button coordinates on thescreen. Program execution then branches out to perform the instructions reservedfor clicking in that space.Object-oriented programming is almost the inverse of that process. A button is con-sidered an object — something tangible. An object has properties, such as its label,size, alignment, and so on. An object may also contain a script. At the same time, thesystem software and browser, working together, can send a message to an object —depending on what the user does — to trigger the script. For example, if a user clicksin a text entry field, the system/browser tells the field that somebody has clickedthere (that is, has set the focus to that field), giving the field the task of decidingwhat to do about it. That’s where the script comes in. The script is connected to thefield, and it contains the instructions that the field carries out after the user acti-vates it. Another set of instructions may control what happens when the user typesan entry and tabs or clicks out of the field, thereby changing the content of the field.Some of the scripts you write may seem to be procedural in construction: Theycontain a simple list of instructions that are carried out in order. But when dealingwith data from form elements, these instructions work with the object-based natureof JavaScript. The form is an object; each radio button or text field is an object aswell. The script then acts on the properties of those objects to get some work done.
    • xvi JavaScript Bible, Gold Edition Making the transition from procedural to object-oriented programming may be the most difficult challenge for you. When I was first introduced to object-oriented pro- gramming a number of years ago, I didn’t get it at first. But when the concept clicked — a long, pensive walk helped — so many light bulbs went on inside my head that I thought I might glow in the dark. From then on, object orientation seemed to be the only sensible way to program. If you’ve programmed in C before By borrowing syntax from Java (which, in turn, is derived from C and C++), JavaScript shares many syntactical characteristics with C. Programmers familiar with C will feel right at home. Operator symbols, conditional structures, and repeat loops follow very much in the C tradition. You will be less concerned about data types in JavaScript than you are in C. In JavaScript, a variable is not restricted to any particular data type. With so much of JavaScript’s syntax familiar to you, you will be able to concentrate on document object model concepts, which may be entirely new to you. You will still need a good grounding in HTML (especially form elements) to put your exper- tise to work in JavaScript. If you’ve programmed in Java before Despite the similarity in their names, the two languages share only surface aspects: loop and conditional constructions, C-like “dot” object references, curly braces for grouping statements, several keywords, and a few other attributes. Variable decla- rations, however, are quite different, because JavaScript is a loosely typed lan- guage. A variable can contain an integer value in one statement and a string in the next (though I’m not saying that this is good style). What Java refers to as methods, JavaScript calls methods (when associated with a predefined object) or functions (for scripter-defined actions). JavaScript methods and functions may return values of any type without having to state the data type ahead of time. Perhaps the most important aspects of Java to suppress when writing JavaScript are the object-oriented notions of classes, inheritance, instantiation, and message pass- ing. These aspects are simply non-issues when scripting. At the same time, however, JavaScript’s designers knew that you’d have some hard-to-break habits. For example, although JavaScript does not require a semicolon at the end of each statement line, if you type one in your JavaScript source code, the JavaScript interpreter won’t balk. If you’ve written scripts (or macros) before Experience with writing scripts in other authoring tools or macros in productivity programs is helpful for grasping a number of JavaScript’s concepts. Perhaps the most important concept is the idea of combining a handful of statements to perform a specific task on some data. For example, you can write a macro in Microsoft Excel that performs a data transformation on daily figures that come in from a corporate financial report on another computer. The macro is built into the Macro menu, and you run it by choosing that menu item whenever a new set of figures arrives.
    • Preface xvii More sophisticated scripting, such as that found in Toolbook or HyperCard, pre- pares you for the object orientation of JavaScript. In those environments, screen objects contain scripts that are executed when a user interacts with those objects. A great deal of the scripting you will do in JavaScript matches that pattern exactly. In fact, those environments resemble the scriptable browser environment in another way: They provide a finite set of predefined objects that have fixed sets of properties and behaviors. This predictability makes learning the entire environ- ment and planning an application easier to accomplish.Formatting and Naming Conventions The script listings and words in this book are presented in a monospace font to set them apart from the rest of the text. Because of restrictions in page width, lines of script listings may, from time to time, break unnaturally. In such cases, the remainder of the script appears in the following line, flush with the left margin of the listing, just as they would appear in a text editor with word wrapping turned on. If these line breaks cause you problems when you type a script listing into a docu- ment yourself, I encourage you to access the corresponding listing on the CD-ROM to see how it should look when you type it. As soon as you reach Part III of this book, you won’t likely go for more than a page before reading about an object model or language feature that requires a specific min- imum version of one browser or another. To make it easier to spot in the text when a particular browser and browser version is required, most browser references consist of a two-letter abbreviation and a version number. For example, IE5 means Internet Explorer 5 for any operating system; NN6 means Netscape Navigator 6 for any operat- ing system. If a feature is introduced with a particular version of browser and is sup- ported in subsequent versions, a plus symbol (+) follows the number. For example, a feature marked IE4+ indicates that Internet Explorer 4 is required at a minimum, but the feature is also available in IE5, IE5.5, and so on. Occasionally, a feature or some highlighted behavior applies to only one operating system. For example, a feature marked IE4+/Windows works only on Windows versions of Internet Explorer 4 or later. As points of reference, the first scriptable browsers were NN2, IE3/Windows, and IE3.01/Macintosh. Moreover, IE3 for Windows can be equipped with one of two versions of the JScript .dll file. A reference to the earlier version is cited as IE3/J1, while the later version is cited as IE3/J2. You will see this notation primarily in the compatibility charts throughout the reference chapters.Note Tip Caution Note, Tip, and Caution icons occasionally appear in the book to flag important points.On the On the CD-ROM icons point you to useful examples and code listings found onCD-ROM this book’s companion CD-ROM.
    • Acknowledgments B efore closing, I would like to acknowledge the contributions of many folks who helped make this edition possible: Eric Krock, Tom Pixley, Vidur Apparao, and especially the ever-patient, all-knowing Brendan Eich (Mozilla); Martin Honnen (Netscape DevEdge Champion); Tantek Celik (Microsoft’s Macintosh development group); Brenda McLaughlin, Walt Bruce, Michael Roney, Debra Williams Cauley, Neil Romanosky, Eric Newman, Cordelia Heaney, Jerelind Charles, and Victoria Lee O’Malley (Hungry Minds, Inc.); technical reviewer David Wall; “cookie man” Bill Dortch (hIdaho Design); Red and his friends (Mars, Incorporated); and fellow scripters and newsgroup kibitzers, who unwittingly advised me as to where scripters were having trouble with the language. Above all, I want to thank the many readers of the first three editions of this book (with both titles, Danny Goodman’s JavaScript Handbook and JavaScript Bible) for investing in this ongoing effort. I wish I had the space here to acknowledge by name so many who have sent e-mail notes and suggestions: Your input has been most welcome and greatly appre- ciated. Now it’s time to get down to the fun of learning JavaScript. Enjoy!
    • Contents at a GlanceForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ixPreface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiAcknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xixPart I: Getting Started with JavaScript . . . . . . . . . . . . . . . . . . . 1Chapter 1: JavaScript’s Role in the World Wide Web and Beyond . . . . . . . . . . 3Chapter 2: Authoring Challenges Amid the Browser Wars . . . . . . . . . . . . . . 11Chapter 3: Your First JavaScript Script . . . . . . . . . . . . . . . . . . . . . . . . . 19Part II: JavaScript Tutorial — Summary . . . . . . . . . . . . . . . . . . 29Chapter 4: Browser and Document Objects . . . . . . . . . . . . . . . . . . . . CD-1Chapter 5: Scripts and HTML Documents . . . . . . . . . . . . . . . . . . . . . CD-23Chapter 6: Programming Fundamentals, Part I . . . . . . . . . . . . . . . . . . CD-35Chapter 7: Programming Fundamentals, Part II . . . . . . . . . . . . . . . . . . CD-47Chapter 8: Window and Document Objects . . . . . . . . . . . . . . . . . . . . CD-61Chapter 9: Forms and Form Elements . . . . . . . . . . . . . . . . . . . . . . . CD-75Chapter 10: Strings, Math, and Dates . . . . . . . . . . . . . . . . . . . . . . . . CD-89Chapter 11: Scripting Frames and Multiple Windows . . . . . . . . . . . . . . CD-99Chapter 12: Images and Dynamic HTML . . . . . . . . . . . . . . . . . . . . . CD-109Part III: Document Objects Reference . . . . . . . . . . . . . . . . . . . 35Chapter 13: JavaScript Essentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Chapter 14: Document Object Model Essentials . . . . . . . . . . . . . . . . . . . 61Chapter 15: Generic HTML Element Objects . . . . . . . . . . . . . . . . . . . . . 105Chapter 16: Window and Frame Objects . . . . . . . . . . . . . . . . . . . . . . . 217Chapter 17: Location and History Objects . . . . . . . . . . . . . . . . . . . . . . 321Chapter 18: The Document and Body Objects . . . . . . . . . . . . . . . . . . . . 339Chapter 19: Body Text Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409Chapter 20: HTML Directive Objects . . . . . . . . . . . . . . . . . . . . . . . . . 473Chapter 21: Link and Anchor Objects . . . . . . . . . . . . . . . . . . . . . . . . . 493Chapter 22: Image, Area, and Map Objects . . . . . . . . . . . . . . . . . . . . . . 505Chapter 23: The Form and Related Objects . . . . . . . . . . . . . . . . . . . . . 527Chapter 24: Button Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549Chapter 25: Text-Related Form Objects . . . . . . . . . . . . . . . . . . . . . . . . 569Chapter 26: Select, Option, and FileUpload Objects . . . . . . . . . . . . . . . . 589Chapter 27: Table and List Objects . . . . . . . . . . . . . . . . . . . . . . . . . . 613Chapter 28: The Navigator and Other Environment Objects . . . . . . . . . . . . 665Chapter 29: Event Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711Chapter 30: Style Sheet and Style Objects . . . . . . . . . . . . . . . . . . . . . . 777
    • Chapter 31: Positioned Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855Chapter 32: Embedded Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 901Chapter 33: XML Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 919Part IV: JavaScript Core Language Reference . . . . . . . . . . . . . . 925Chapter 34: The String Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927Chapter 35: The Math, Number, and Boolean Objects . . . . . . . . . . . . . . . 951Chapter 36: The Date Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 967Chapter 37: The Array Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 987Chapter 38: The Regular Expression and RegExp Objects . . . . . . . . . . . . 1007Chapter 39: Control Structures and Exception Handling . . . . . . . . . . . . . 1033Chapter 40: JavaScript Operators . . . . . . . . . . . . . . . . . . . . . . . . . . 1069Chapter 41: Functions and Custom Objects . . . . . . . . . . . . . . . . . . . . 1093Chapter 42: Global Functions and Statements . . . . . . . . . . . . . . . . . . . 1127Part V: Putting JavaScript to Work . . . . . . . . . . . . . . . . . . . . 1147Chapter 43: Data-Entry Validation . . . . . . . . . . . . . . . . . . . . . . . . . . 1149Chapter 44: Scripting Java Applets and Plug-ins . . . . . . . . . . . . . . . . . . 1177Chapter 45: Debugging Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217Chapter 46: Security and Netscape Signed Scripts . . . . . . . . . . . . . . . . . 1239Chapter 47: Cross-Browser Dynamic HTML Issues . . . . . . . . . . . . . . . . 1259Chapter 48: Internet Explorer Behaviors . . . . . . . . . . . . . . . . . . . . . . 1273Chapter 49: Application: Tables and Calendars . . . . . . . . . . . . . . . . . . 1285Chapter 50: Application: A Lookup Table . . . . . . . . . . . . . . . . . . . . . . 1299Chapter 51: Application: A “Poor Man’s” Order Form . . . . . . . . . . . . . . . 1311Chapter 52: Application: Outline-Style Table of Contents . . . . . . . . . . . . . 1321Chapter 53: Application: Calculations and Graphics . . . . . . . . . . . . . . . 1355Chapter 54: Application: Intelligent “Updated” Flags . . . . . . . . . . . . . . . 1365Chapter 55: Application: Decision Helper . . . . . . . . . . . . . . . . . . . . . . 1375Chapter 56: Application: Cross-Browser DHTML Map Puzzle . . . . . . . . . . 1399Chapter 57: Application: Transforming XML Data Islands . . . . . . . . . . . . 1415Part VI: Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431Appendix A: JavaScript and Browser Object Quick Reference . . . . . . . . . . 1433Appendix B: JavaScript Reserved Words . . . . . . . . . . . . . . . . . . . . . . 1447Appendix C: Answers to Tutorial Exercises . . . . . . . . . . . . . . . . . . . . . 1449Appendix D: JavaScript and DOM Internet Resources . . . . . . . . . . . . . . . 1465Appendix E: What’s on the CD-ROM . . . . . . . . . . . . . . . . . . . . . . . . . 1469Appendix F: Examples from Parts III and IV . . . . . . . . . . . . . . . . . . . CD-117Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1473End User License Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1512CD-ROM Installation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 1516
    • Contents Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xixPart I: Getting Started with JavaScript 1 Chapter 1: JavaScript’s Role in the World Wide Web and Beyond . . . 3 Competition on the Web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Hypertext Markup Language (HTML) . . . . . . . . . . . . . . . . . . . . . . . 4 CGI Scripting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Of Helpers and Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Java Applets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 JavaScript: A Language for All . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 JavaScript: The Right Tool for the Right Job . . . . . . . . . . . . . . . . . . . 9 Chapter 2: Authoring Challenges Amid the Browser Wars . . . . . . . 11 Leapfrog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Duck and Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Compatibility Issues Today . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Developing a Scripting Strategy . . . . . . . . . . . . . . . . . . . . . . . . . 16 Chapter 3: Your First JavaScript Script . . . . . . . . . . . . . . . . . . . 19 The Software Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Setting Up Your Authoring Environment . . . . . . . . . . . . . . . . . . . . 20 What Your First Script Will Do . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Entering Your First Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Examining the Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Have Some Fun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Part II: JavaScript Tutorial — Summary 29 Chapter 4: Browser and Document Objects . . . . . . . . . . . . . . CD-1 Scripts Run the Show . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-1 JavaScript in Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-2
    • xxiv JavaScript Bible, Gold Edition The Document Object Model . . . . . . . . . . . . . . . . . . . . . . . . . CD-8 When a Document Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-11 Object References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-14 About the Dot Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-17 What Defines an Object? . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-18 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-21 Chapter 5: Scripts and HTML Documents . . . . . . . . . . . . . . CD-23 Where Scripts Go in Documents . . . . . . . . . . . . . . . . . . . . . . . CD-23 JavaScript Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-27 When Script Statements Execute . . . . . . . . . . . . . . . . . . . . . . . CD-28 Viewing Script Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-30 Scripting versus Programming . . . . . . . . . . . . . . . . . . . . . . . . CD-32 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-33 Chapter 6: Programming Fundamentals, Part I . . . . . . . . . . . CD-35 What Language Is This? . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-35 Working with Information . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-35 Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-36 Expressions and Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . CD-38 Data Type Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-40 Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-42 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-44 Chapter 7: Programming Fundamentals, Part II . . . . . . . . . . . CD-47 Decisions and Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-47 Control Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-48 About Repeat Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-50 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-51 About Curly Braces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-54 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-55 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-59 Chapter 8: Window and Document Objects . . . . . . . . . . . . . CD-61 Document Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-61 The Window Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-62 Window Properties and Methods . . . . . . . . . . . . . . . . . . . . . . CD-65 The Location Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-68 The History Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-69 The Document Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-69 The Link Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-73 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-73
    • Contents xxv Chapter 9: Forms and Form Elements . . . . . . . . . . . . . . . . . CD-75 The FORM Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-75 Form Controls as Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-77 The Button Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-79 The Checkbox Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-79 The Radio Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-80 The SELECT Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-82 Passing Form Data and Elements to Functions . . . . . . . . . . . . . . . CD-83 Submitting and Prevalidating Forms . . . . . . . . . . . . . . . . . . . . . CD-85 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-87 Chapter 10: Strings, Math, and Dates . . . . . . . . . . . . . . . . . CD-89 Core Language Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-89 String Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-90 The Math Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-93 The Date Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-94 Date Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-96 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-97 Chapter 11: Scripting Frames and Multiple Windows . . . . . . . CD-99 Frames: Parents and Children . . . . . . . . . . . . . . . . . . . . . . . . CD-99 References among Family Members . . . . . . . . . . . . . . . . . . . . CD-101 Frame Scripting Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-103 Controlling Multiple Frames — Navigation Bars . . . . . . . . . . . . . CD-103 More about Window References . . . . . . . . . . . . . . . . . . . . . . CD-106 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-107 Chapter 12: Images and Dynamic HTML . . . . . . . . . . . . . . CD-109 The Image Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-109 More Dynamism in HTML . . . . . . . . . . . . . . . . . . . . . . . . . . CD-115 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-116Part III: Document Objects Reference 35 Chapter 13: JavaScript Essentials . . . . . . . . . . . . . . . . . . . . . 37 JavaScript Versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Core Language Standard — ECMAScript . . . . . . . . . . . . . . . . . . . . . 38 Embedding Scripts in HTML Documents . . . . . . . . . . . . . . . . . . . . 38 Browser Version Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Designing for Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Language Essentials for Experienced Programmers . . . . . . . . . . . . . . 57 Onward to Object Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
    • xxvi JavaScript Bible, Gold Edition Chapter 14: Document Object Model