HTML5 Mobile Application Development in 24 hours

会飞的鱼

贡献于2013-10-16

字数:0 关键词: HTML5 前端技术 HTML

ptg999 ptg999 800 East 96th Street, Indianapolis, Indiana, 46240 USA Jennifer Kyrnin SamsTeach Yourself 24in Hours HTML5 Mobile Application Development ptg999 Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours Copyright © 2012 by Pearson Education, Inc. All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions. Nor is any liability assumed for damages resulting from the use of the information contained herein. ISBN-13: 978-0-672-33440-5 ISBN-10: 0-672-33440-2 Library of Congress Cataloging-in-Publication Data: Kyrnin, Jennifer. Sams teach yourself HTML5 mobile application development in 24 hours / Jennifer Kyrnin. p. cm. Includes bibliographical references and index. ISBN 978-0-672-33440-5 (pbk. : alk. paper) 1. HTML (Document markup language) 2. Mobile computing—Programming. 3. Application software—Development. I. Title. QA76.76.H94K97 2012 006.7’4—dc23 2011036380 Printed in the United States of America First Printing: November 2012 Trademarks All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Sams Publishing cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. Warning and Disclaimer Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information provided is on an “as is” basis. The author and the publisher shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or programs accompanying it. Bulk Sales Sams Publishing offers excellent discounts on this book when ordered in quantity for bulk pur- chases or special sales. For more information, please contact U.S. Corporate and Government Sales 1-800-382-3419 corpsales@pearsontechgroup.com For sales outside of the U.S., please contact International Sales international@pearson.com Editor-in-Chief Mark Taub Acquisitions Editor Trina MacDonald Development Editor Michael Thurston Managing Editor Kristy Hart Project Editors Jovana San Nicolas-Shirley and Jess DeGabriele Copy Editor Paula Lowell Senior Indexer Cheryl Lenser Proofreader Leslie Joseph Technical Editors Evan Burchard Pascal Rettig Publishing Coordinator Olivia Basegio Cover Designer Gary Adair Compositor Nonie Ratcliff ptg999 Contents at a Glance Preface ................................................................................. xiv Part I: Building Web Pages and Applications with the Open Web Standard HOUR 1 Improving Mobile Web Application Development with HTML5 ........ 1 2 New HTML5 Tags and Attributes with Mobile Development ........... 15 3 Styling Mobile Pages with CSS3 ................................................. 33 4 Detecting Mobile Devices and HTML5 Support............................. 49 5 JavaScript and HTML5 Web Applications .................................... 67 6 Building a Mobile Web Application ........................................... 85 7 Upgrading a Site to HTML5..................................................... 105 8 Converting Web Apps to Mobile .............................................. 119 Part II: Learning the HTML5 Essentials HOUR 9 Adding Meaning with HTML5 Sectioning and Semantic Elements . 141 10 Drawing with the HTML5 Canvas Element ................................ 163 11 Fonts and Typography in HTML5............................................. 187 12 Audio and Video in HTML5 .................................................... 205 13 HTML5 Forms ....................................................................... 223 14 Editing Content and User Interaction with HTML5 ...................... 245 15 Microformats and Microdata................................................... 261 16 Working with HTML5 Drag-and-Drop Functionality .................... 275 17 HTML5 Links ........................................................................ 293 Part III: HTML5 for Mobile and Web Applications HOUR 18 Web Application APIs and Datasets.......................................... 309 19 WebSockets, Web Workers, and Files ......................................... 323 20 Offline Web Applications........................................................ 341 21 Web Storage in HTML5........................................................... 355 22 Controlling the Browser History with the History API .................. 373 ptg999 23 Adding Location Detection with Geolocation ............................. 387 24 Converting HTML5 Apps to Native Apps ................................... 405 Appendixes A Answers to Quizzes ................................................................ 423 B HTML Elements and Attributes ................................................ 437 C HTML5 and Mobile Application Resources................................. 447 Index ............................................................................................449 iv Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours ptg999 Table of Contents Preface ............................................................................................ xiv Part I: Building Web Pages and Applications with the Open Web Standard HOUR 1: Improving Mobile Web Application Development with HTML5 1 Understanding How We Got to HTML5 .................................................... 1 Learning What’s Different with HTML5 .................................................... 3 Defining Web Applications .................................................................... 4 Using the Open Web Standard................................................................ 4 Using HTML5 with iOS and Android Devices ............................................ 6 Writing Mobile Websites ........................................................................ 7 Summary .......................................................................................... 11 Q&A ................................................................................................ 12 Workshop .......................................................................................... 13 HOUR 2: New HTML5 Tags and Attributes with Mobile Development 15 The New HTML5 Tags.......................................................................... 15 The New HTML5 Attributes .................................................................. 24 Changes to HTML 4 Tags and Attributes ................................................ 25 Changes to HTML Syntax in HTML5 ...................................................... 27 Mobile Support of HTML5 Tags and Attributes ........................................ 28 Benefits of HTML5 for Mobile Web Development...................................... 29 Summary .......................................................................................... 30 Q&A ................................................................................................ 30 Workshop .......................................................................................... 31 HOUR 3: Styling Mobile Pages with CSS3 33 Quick Introduction to CSS .................................................................... 33 What CSS3 Adds to the Party ................................................................ 42 Using CSS3 on Mobile Devices .............................................................. 46 ptg999 Summary .......................................................................................... 46 Q&A ................................................................................................ 46 Workshop .......................................................................................... 47 HOUR 4: Detecting Mobile Devices and HTML5 Support 49 Choosing What HTML5 Elements to Use ................................................ 50 Android and iOS Support for HTML5 .................................................... 50 Detecting HTML5 Functions.................................................................. 52 Degrading Gracefully .......................................................................... 58 Using CSS3 Media Queries to Detect Mobile Browsers................................ 60 Testing Your Applications .................................................................... 63 Summary .......................................................................................... 64 Q&A ................................................................................................ 64 Workshop .......................................................................................... 65 HOUR 5: JavaScript and HTML5 Web Applications 67 What is JavaScript? ............................................................................ 67 What is jQuery? ................................................................................ 72 Using jQuery Mobile .......................................................................... 79 Summary .......................................................................................... 82 Q&A ................................................................................................ 82 Workshop .......................................................................................... 83 HOUR 6: Building a Mobile Web Application 85 Building a Site that Works on All Devices .............................................. 85 Deciding on What Type of Application You Want .................................... 86 Building the Application in HTML ........................................................ 89 Using CSS to Make the HTML Look Good................................................ 91 Adding Mobile Meta Tags for More Effective HTML5 Pages ........................ 96 Optimizing Your Site for Mobile ............................................................ 99 Summary ........................................................................................ 102 Q&A .............................................................................................. 102 Workshop ........................................................................................ 103 vi Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours ptg999 HOUR 7: Upgrading a Site to HTML5 105 Deciding When and How to Upgrade from HTML 4 ................................ 105 HTML5 Features that Work Right Now.................................................. 111 The State of HTML5 Browser Support.................................................... 112 Adding HTML5 Features as Extras on Your Site ...................................... 113 HTML5 Features that Turn Your Site into a Killer Mobile Application ........ 115 Summary ........................................................................................ 116 Q&A .............................................................................................. 116 Workshop ........................................................................................ 118 HOUR 8: Converting Web Apps to Mobile 119 Choosing a Web Editor ...................................................................... 120 Testing Your Application .................................................................... 121 Evaluating Your Content .................................................................... 123 Changing the Visual Design for Mobile ................................................ 124 Checking for HTML5 and CSS3............................................................ 130 Supporting Multiple Devices .............................................................. 132 Evaluating Finished Apps on Other Devices .......................................... 133 Getting an Application to Work on Older Browsers ................................ 134 Summary ........................................................................................ 138 Q&A .............................................................................................. 139 Workshop ........................................................................................ 139 Part II: Learning the HTML5 Essentials HOUR 9: Adding Meaning with HTML5 Sectioning and Semantic Elements 141 What Are Sectioning Elements? .......................................................... 141 Using the New Sectioning Elements ...................................................... 142 Marking Up HTML Semantically.......................................................... 154 Summary ........................................................................................ 159 Q&A .............................................................................................. 159 Workshop ........................................................................................ 160 Contents vii ptg999 HOUR 10: Drawing with the HTML5 Canvas Element 163 Using the Canvas Element .................................................................. 163 Drawing Shapes on the Element............................................ 165 Writing Fonts and Text on the Canvas .................................................. 177 Displaying Images ............................................................................ 179 How Is Canvas Different from SVG or Flash .......................................... 182 Summary ........................................................................................ 183 Q&A .............................................................................................. 184 Workshop ........................................................................................ 185 HOUR 11: Fonts and Typography in HTML5 187 Defining the Elements of Typography .................................................. 187 Using Proper Typographical Entities .................................................... 196 Understanding Web Open Font Format (WOFF)...................................... 198 Summary ........................................................................................ 202 Q&A .............................................................................................. 202 Workshop ........................................................................................ 203 HOUR 12: Audio and Video in HTML5 205 Why Use HTML5 for Audio and Video vs. Flash...................................... 205 Choosing Video Formats for the Best Compatibility ................................ 207 Choosing Audio Codecs for the Widest Support ...................................... 208 The New HTML5 Media Elements ........................................................ 210 Useful Attributes to Extend Your Media ................................................ 212 Creating Fallback Options for Internet Explorer .................................... 216 Creating Custom Controls with API Methods ........................................ 217 Summary ........................................................................................ 219 Q&A .............................................................................................. 220 Workshop ........................................................................................ 220 HOUR 13: HTML5 Forms 223 New Usability Features in HTML5 Forms .............................................. 223 HTML5 Input Types .......................................................................... 228 Other New Form Elements .................................................................. 235 viii Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours ptg999 Form Validation................................................................................ 237 Summary ........................................................................................ 241 Q&A .............................................................................................. 242 Workshop ........................................................................................ 242 HOUR 14: Editing Content and User Interaction with HTML5 245 The New contenteditable Attribute .................................................. 245 The execCommand Method .................................................................. 247 Adding Spellcheck to Web Pages .......................................................... 251 Hiding Elements .............................................................................. 252 Additional UI Components of HTML5 .................................................. 253 Browser Support of UI and Editing Features .......................................... 255 Summary ........................................................................................ 257 Q&A .............................................................................................. 258 Workshop ........................................................................................ 258 HOUR 15: Microformats and Microdata 261 Using Microformats .......................................................................... 261 Using Microdata .............................................................................. 267 Using RDFa ...................................................................................... 269 Deciding Which Format to Use ............................................................ 270 Mobile and Microformats .................................................................. 271 Summary ........................................................................................ 272 Q&A .............................................................................................. 273 Workshop ........................................................................................ 274 HOUR 16: Working with HTML5 Drag-and-Drop Functionality 275 Implementing Drag and Drop ............................................................ 275 Drag-and-Drop Events ...................................................................... 276 Drag-and-Drop Attributes .................................................................. 279 Helpful CSS Extensions ...................................................................... 280 Building a Drag-and-Drop Interface .................................................... 280 Using Drag and Drop on iOS .............................................................. 287 Contents ix ptg999 Summary ........................................................................................ 290 Q&A .............................................................................................. 290 Workshop ........................................................................................ 291 HOUR 17: HTML5 Links 293 How Links Have Changed in HTML5.................................................... 293 Link Types and Relationships .............................................................. 299 Using the New Link Types .................................................................. 300 Summary ........................................................................................ 306 Q&A .............................................................................................. 306 Workshop ........................................................................................ 307 Part III: HTML5 for Mobile and Web Applications HOUR 18: Web Application APIs and Datasets 309 Creating Web Applications ................................................................ 309 Datasets and data-* Attributes .......................................................... 318 Summary ........................................................................................ 320 Q&A .............................................................................................. 320 Workshop ........................................................................................ 321 HOUR 19: WebSockets, Web Workers, and Files 323 Two-Way Communication with WebSockets .......................................... 323 Running Scripts in the Background with Web Workers ............................ 326 Handling Client-Side Files with the File API .......................................... 331 Summary ........................................................................................ 337 Q&A .............................................................................................. 338 Workshop ........................................................................................ 339 HOUR 20: Offline Web Applications 341 Building Offline Apps and Converting Apps to Work Offline .................... 341 The Cache Manifest .......................................................................... 343 Using DOM Events and Properties for Offline Apps ................................ 347 Debugging the Application Cache ...................................................... 351 x Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours ptg999 Summary ........................................................................................ 352 Q&A .............................................................................................. 352 Workshop ........................................................................................ 353 HOUR 21: Web Storage in HTML5 355 What Is Web Storage? ........................................................................ 356 Web SQL and Indexed DB .................................................................. 361 Summary ........................................................................................ 370 Q&A .............................................................................................. 371 Workshop ........................................................................................ 372 HOUR 22: Controlling the Browser History with the History API 373 Why Control the Browser History? ...................................................... 373 History API Methods.......................................................................... 375 Using the History API ........................................................................ 375 Dangers and Annoyances of the History API ........................................ 383 Summary ........................................................................................ 384 Q&A .............................................................................................. 385 Workshop ........................................................................................ 386 HOUR 23: Adding Location Detection with Geolocation 387 What Is Geolocation? ........................................................................ 387 Privacy and Geolocation .................................................................... 394 Creating a Mobile Geolocation Application .......................................... 396 Summary ........................................................................................ 401 Q&A .............................................................................................. 401 Workshop ........................................................................................ 402 HOUR 24: Converting HTML5 Apps to Native Apps 405 Comparing the Difference Between Native and HTML5 Apps .................. 405 Converting to Native Apps ................................................................ 408 Creating Application Icons ................................................................ 414 Testing Your Applications .................................................................. 416 Selling Your App in the App Stores ...................................................... 418 Contents xi ptg999 Options Other Than Converting to Native Apps .................................... 419 Summary ........................................................................................ 419 Q&A .............................................................................................. 420 Workshop ........................................................................................ 421 Part IV: Appendixes APPENDIX A: Answers to Quizzes 423 Hour 1, “Improving Mobile Web Application Development with HTML5” .................................................................................. 423 Hour 2, “New HTML5 Tags and Attributes with Mobile Development” ...... 423 Hour 3, “Styling Mobile Pages with CSS3” ............................................ 424 Hour 4, “Detecting Mobile Devices and HTML5 Support” ........................ 424 Hour 5, “JavaScript and HTML5 Web Applications” ................................ 425 Hour 6, “Building a Mobile Web Application” ...................................... 425 Hour 7, “Upgrading a Site to HTML5” .................................................. 426 Hour 8, “Converting Web Apps to Mobile” ............................................ 426 Hour 9, “Adding Meaning with HTML5 Sectioning and Semantic Elements” .......................................................................... 427 Hour 10, “Drawing with the HTML5 Canvas Element” ............................ 427 Hour 11, “Fonts and Typography in HTML5” ........................................ 428 Hour 12, “Audio and Video in HTML5” ................................................ 428 Hour 13, “HTML5 Forms” .................................................................. 429 Hour 14, “Editing Content and User Interaction with HTML5” .................. 429 Hour 15, “Microformats and Microdata” .............................................. 430 Hour 16, “Working with HTML5 Drag-and-Drop Functionality” ................ 430 Hour 17, “HTML5 Links” .................................................................... 430 Hour 18, “Web Application APIs and Datasets”...................................... 431 Hour 19, “WebSockets, Web Workers, and Files” .................................... 431 Hour 20, “Offline Web Applications”.................................................... 432 Hour 21, “Web Storage in HTML5” ...................................................... 432 xii Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours ptg999 Hour 22, “Controlling the Browser History with the History API” .............. 433 Hour 23, “Adding Location Detection with Geolocation” ........................ 434 Hour 24, “Converting HTML5 Apps to Native Apps” .............................. 434 APPENDIX B: HTML Elements and Attributes 437 HTML5 Elements .............................................................................. 437 HTML5 Attributes.............................................................................. 442 APPENDIX C: HTML5 and Mobile Application Resources 447 Books .............................................................................................. 447 Websites .......................................................................................... 448 This Book’s Website .......................................................................... 448 Index 449 Contents xiii ptg999 Preface The web is changing very quickly these days. New browser versions are being released every few months rather than every few years, and new devices are entering the marketplace all the time. For a web developer, staying up to date on the latest trends and technology is important, and the trending technology right now is HTML5. In fact, some news outlets are claiming that HTML5 and mobile applications are two of the fastest-growing areas of job creation. According to Freelancer.com and iTWire, requests for freelancers knowing HTML5 rose by 34% in the first quarter of 2011, while general HTML jobs rose only by 7%. They also noted that Android jobs rose by 20%, and iPhone jobs rose by 9%.1 HTML5 and mobile applications are where the jobs are, and this book can help you learn all about HTML5 and the application programming interfaces (APIs) that relate to it. After 24 hours, you will be able to build complex web applications and convert them into native mobile applications. HTML5 Is More Than HTML This book covers more than HTML tags and attributes. Although these things are the basis of the HTML5 specification, when people talk about HTML5 they often include many other programming interfaces that are not strictly part of the HTML5 specification, like geoloca- tion or the History API. This book covers the basics of HTML5 and how it has changed from previous versions of HTML. It also introduces you to some of the technologies that are lumped in with HTML5, including: . Drawing with the canvas element . Adding streaming media with the video and audio elements . Editing pages online and checking spelling . Using drag-and-drop functions on web applications 1 “Freelancer.com job listings show growth in HTML5, Adsense, and Android.” iTWire. July 11, 2011. www.itwire.com/it-people-news/recruitment/48392-freelancercom-job-listings-show-growth-in-html5- adsense-and-android. July 25, 2011. ptg999 . Building more user-friendly forms . Creating semantic divisions with new elements, such as article, section, and nav This book covers several other specifications beyond HTML5, including: . Web Open Font Format (WOFF) web fonts . Microformats and Microdata . WebSockets . Web Workers . Files API . Web Storage . Offline Web Applications API . History API . Geolocation Web Pages Are for More Than Computers HTML used to be used primarily in web browsers on computers, but now, with the advent of smartphones and tablet computers, more people are accessing web pages on mobile devices. Every hour of this book provides examples of how the lesson’s contents apply both to web browsers and mobile devices and shows you techniques for getting your applications to look better on mobile devices. With this book, you will learn how to create applications that work on the most popular mobile smartphones and tablets out there: Android and iOS (iPhone, iPad, and iPod touch devices). Screenshots from both Android and iOS devices appear throughout as well as tips and warnings about how the different devices perform. How to Use This Book This book is divided into 24 lessons. Each lesson covers a specific topic related to HTML5 or an API that is part of the Open Web Standard. Each lesson takes about an hour to complete. Preface xv ptg999 xvi Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours Organization of This Book This book is divided into three sections: . Part I, “Building Web Pages and Applications with the Open Web Standard,” teaches you the basics of HTML, CSS, and JavaScript, and teaches you how to build a basic web application for mobile and non-mobile devices. After reading this section, you will know how to build a basic website with HTML, CSS, and JavaScript. . Part II, “Learning the HTML5 Essentials,” covers some of the more important new fea- tures of HTML5. You will learn more about new HTML5 elements to help you build better applications. . Part III, “HTML5 for Mobile and Web Applications,” describes some of the more useful APIs and tools for mobile application development and goes into detail about how to create mobile applications. Conventions Used in This Book Code samples are written in mono font within the text of the book, while blocks of code will be called out separately, for example: This is a block Of code Some code examples that are too long to display as one line in the book use the ➥ symbol to indicate that these lines should be all on one line, like this: This book has three types of sidebars: By the Way notes provide additional information about the topics that are discussed in the hour. Did you Know? tips share interesting facts or tidbits about the related content. Watch Out! warnings alert you of things that can cause problems for your applications. By theWay Did youKnow? WatchOut! ptg999 ▼ Preface xvii You can also use the Try It Yourself sections to help you practice what you’ve learned in the hour. Try It Yourself Nearly every hour will have at least one step-by-step tutorial called “Try It Yourself” to help you use what you’ve learned. Q&A, Quiz, and Exercises Every hour ends with a short question-and-answer section to help with follow-up questions that occur as a result of reading the hour. You can also take a short quiz on the hour (Appendix A provides the answers) as well as do some suggested exercises to help you get more out of what you learned and apply this knowledge to your own applications. Where to Go to Learn More Appendix C includes more websites and books you can access to learn more about HTML5 and mobile web applications. This book also has a companion website at www. html5in24hours.com/ where you can go to see the examples, view and download the source code for each hour, view and report errata about the book, and continue to learn and ask questions about HTML5 mobile applications. ▲ ptg999 xviii Sams Teach Yourself HTML5 Mobile Application Development in 24 Hours About the Author Jennifer Kyrnin has been teaching HTML, XML, and web design online since 1997. She has built and maintained websites of all sizes from small, single-page brochure sites to large, million-page databased sites for international audiences. She lives with her husband, son, and numerous animals on a small farm in Washington state. Dedication To Mark and Jaryth, you helped me find time I didn’t know I had. I love you. Acknowledgments I would like to thank all the people at Sams for the opportunity to write this book and work with you. I would particularly like to thank Trina MacDonald and Olivia Basegio for keep- ing me moving and the book on track as well as my two fabulous technical editors Pascal Rettig and Evan Burchard for all the great suggestions and corrections. Any technical errors you find in the book are mine alone; they probably tried to stop me. I would also like to thank my family for putting up with me while I wrote the book, and the members of the Woodinville Writers Group, without whom I would have felt very alone as I hunkered down writing. ptg999 Reader Services xix We Want to Hear from You! As the reader of this book, you are our most important critic and commentator. We value your opinion and want to know what we’re doing right, what we could do better, what areas you’d like to see us publish in, and any other words of wisdom you’re willing to pass our way. You can email or write me directly to let me know what you did or didn’t like about this book—as well as what we can do to make our books stronger. Please note that I cannot help you with technical problems related to the topic of this book, and that due to the high volume of mail I receive, I might not be able to reply to every message. When you write, please be sure to include this book’s title and author as well as your name and phone or email address. I will carefully review your comments and share them with the author and editors who worked on the book. E-mail: webdev@samspublishing.com Mail: Mark Taub Editor-in-Chief Pearson Education 1330 6th Avenue New York, NY 10019 USA Reader Services Visit our website and register this book at informit.com/register for convenient access to any updates, downloads, or errata that might be available for this book. ptg999 This page intentionally left blank ptg999 Understanding 1 HOUR 1 Improving Mobile Web Application Development with HTML5 What You’ll Learn in This Hour: . How HTML has grown and changed since it was invented . Where HTML5 fits in with the other versions of HTML . What the Open Web Standard is and how it relates to HTML5 . How a web application differs from typical web pages . How to build a very simple HTML5 web page . Why you want to use HTML5 for your mobile applications HTML5 is the latest version of HTML, and although adoption on desktop browsers such as Internet Explorer is slow, mobile devices are jumping on the bandwagon in record numbers. Nearly every smartphone and tablet device sold today supports HTML5, and those numbers are growing. In this hour you will learn how HTML5 came into being and how it has changed the landscape for web designers and developers as well as the customers viewing your pages. You’ll learn to build a simple HTML5 document and why HTML5 is the language you should know if you want to design and develop mobile applications. Understanding How We Got to HTML5 In March 1989, Sir Tim Berners-Lee wrote a proposal that suggested using hypertext to link related documents together over a network. After collaborating with others at CERN, hypertext eventually became HTML or Hypertext Markup Language. HTML was based on a language already in use for marking up documents—SGML (Standard Generalized Markup Language). In September 1991, a discussion began across the internet about how the web and HTML should evolve. ptg999 2 HOUR 1: Improving Mobile Web Application Development with HTML5 Up until around 1993, the only browser available was a text-only browser called Lynx. Then Mosaic came out with features such as images, nested lists, and forms. Most designers these days take these things for granted, but back in the early 1990s many people browsed the web in a black-and-white (or green-and-black), text-only environment. Getting a browser to support images was very exciting. It wasn’t until 1994 that the HTML working group was set up by the IETF (Internet Engineering Task Force). In July it released a working draft of HTML 2. Later that year, the W3C, or World Wide Web Consortium, was formed at MIT to act as a standards body for HTML. HTML 3 was released as a draft in 1995, and HTML 3.2 was endorsed as a standard in 1997. HTML 4 was published as a recommendation in 1999. XML and XHTML After 1999 things began to change. The W3C no longer felt that HTML should remain as it was. Instead, they wanted to make it more machine-readable, more consistent, and much stricter. So, rather than working on a new version of HTML, they began turning HTML into a strict markup language called XHTML. XHTML was created as a version of HTML 4.01 that was rewritten in XML (eXtensible Markup Language). It was developed in 1998 as a way to create markup languages that are machine readable. XHTML documents must be well formed and valid. In fact, the W3C wanted all browsers that read XHTML to stop rendering the page if the page’s HTML was not valid or well-formed. XML is still used by many companies. For example, many content management sys- tems (CMSs) use XML on the back end to manage large websites; many books are written in DocBook, which is an XML language for publishing; and ePub books use XML to create ebooks. Well-Formed Versus Valid A document that is well-formed has the declaration statement at the top— including the specification, all attributes are surrounded by quotation marks, all elements are closed, and there is only one container element. A document that is valid is one that is checked against the specification and has no errors. By theWay HTML5 is Born XHTML, because it is based on XML, has the same strict requirements as XML, which makes XHTML very difficult to write. Although most web designers recognize the importance of creating HTML that is valid, at the end of the day the most important thing is that the HTML works in readers’ browsers. Every beginning web designer ptg999 Learning What’s Different with HTML5 3 who has ever validated a page knows that just because a page isn’t valid doesn’t mean browsers won’t be able to display it. In fact, web browsers have no problem displaying technically invalid HTML. Because of these difficulties, a group of web designers and developers as well as browser makers and others got together in 2004 and formed the Web Hypertext Application Technology Working Group (WHATWG). They started building the HTML5 specification to address the needs of designers, developers, and browser mak- ers. Finally, in 2008, the W3C decided to scrap XHTML development in favor of reintegrating with the HTML5 community, and added the HTML5 specification into the W3C framework. Learning What’s Different with HTML5 HTML 4 is the last recommendation developed by the W3C alone. Most web pages right now are built in HTML 4 because it is widely supported by web browsers and editors. XHTML was created by rewriting the HTML 4.01 specification as XML, which means that all tags must be closed, the XHTML tags must be written in all lowercase, all attributes must have quotation marks around them, and tags must be nested with- out overlapping. Nesting Tags Correctly When you nest two HTML tags, you should think of them as a stack of bowls—one inside the other. Always close the nested tag first, and then close the outer tag. Incorrect: This text is italic, and this is bold and italic Correct: This text is italic, and this is bold and italic HTML5 goes back to a less restrictive version of HTML. End tags are no longer required for all elements, you can write in upper- or lowercase, and attributes don’t need to have quotations around them all the time. HTML5 also adds a lot of new elements, including a streamlined doctype (or DTD— the first line of your HTML document. It tells the browser that this document is an HTML5 one), sectioning elements, many new form features, and support for drag and drop and other features useful for creating web applications. ptg999 4 HOUR 1: Improving Mobile Web Application Development with HTML5 A New HTML5 Doctype HTML5 has a new streamlined doctype that is very easy to remember— . Nothing else is required. It doesn’t even have to be written in all caps. Did youKnow? Defining Web Applications Applications are software programs that are used on a local computer to do various tasks. The most commonly used applications are web browsers (such as Internet Explorer or Firefox), document editors (such as Word), and email clients (such as Outlook or Thunderbird). These programs are very similar to one another because they all run on the same operating system. They have features such as . A similar look and feel, such as the menus at the top . Functionality such as drag-and-drop, saving to the hard drive, and interactivity Web applications are web pages that are attempting to look and act like desktop applications. They are written to run inside a web browser, rather than directly on the computer. This means that they are limited by the functions that the web brows- er can and cannot do: . Web applications rely on the web browser for functionality that would otherwise have to be coded (such as the back button, rendering the page, and so on). . Web applications are limited the same way a browser is limited. They can’t save data to the hard drive, they have only limited scripting functions, and they can’t interact directly with the computer operating system. Web applications, unlike desktop applications, are not limited to one operating sys- tem. A web application runs in a browser, and so anywhere a browser will run, the web application will run. Using the Open Web Standard HTML5 was written primarily as a way to develop better, more efficient web applica- tions, and it is part of the suite of APIs and specifications developed under the Open Web Standard. The Open Web Standard or Open Web Platform is a collection of royalty-free technologies that enable the web. ptg999 ▼ Using the Open Web Standard 5 Did youKnow? Many people think HTML5 includes more than it does. In fact, features such as the History API (discussed in Hour 22, “Controlling the Browser History with the History API”), local storage (Hour 21, “Web Storage in HTML5”), and geolocation (Hour 23, “Adding Location Detection with Geolocation”) are all separate specifications that work with HTML5 to create a suite of tools you can use to build web pages, web applications, mobile applications, and more. These all are part of the Open Web Standard. Some of the specifications in this standard include: . HTML5 . CSS3 . Web Fonts . HTML Canvas . SVG . Web storage . Geolocation By using standards-based specifications for your web applications, you will know that your pages and applications will work for a wider audience, and that your pages and applications will last longer. Try It Yourself Building Your First HTML5 Document HTML5 is, at its heart, HTML, which is what you use to build web pages. So before you can get started on the applications that you’ll develop in later hours, you need to know how to build a web page. You start by writing some HTML, which is very easy to write. All you need is a text editor. Finding Your Computer’s Text Editor If you have access to a computer, you have access to a text editor for writing HTML. On Windows type in Notepad in the Search programs and files box in your Start menu. On Macintosh, type in TextEdit in the Spotlight. Use either the vi or Emacs command on a Linux computer. ptg999 6 HOUR 1: Improving Mobile Web Application Development with HTML5 WatchOut! After you have a text editor up and running, you can begin writing your HTML, which is defined by tags that are written inside of less-than (<) and greater-than (>) signs. 1. Open your text editor and type the following: This is my first HTML5 page

My First HTML Document

This is my first HTML5 document. 2. Save your file as mypage.html. Check That File Extension Make sure to check the extension of your HTML file in your file system. Notepad will often convert it to a .txt file if you aren’t careful. If it does, simply close Notepad and replace the .txt extension with .html. 3. Now open this page in your favorite web browser (by browsing to it in the File menu) to test that your page displays correctly. If it doesn’t display correctly, you’ll need to check that you opened the right file and that you wrote the HTML correctly. As you can see from the missing closing tags, the HTML is not nearly as strict as XHTML, and the first line (the doctype or DTD) is simple to use and easy to remember. Using HTML5 with iOS and Android Devices Many designers are reluctant to get started using HTML5 on their web pages because Internet Explorer has relatively little support for it. In fact, only Internet Explorer 9 has decent HTML5 support. Other computer browsers, such as Firefox, Chrome, Opera, and Safari, all have good support for most HTML5 features. ▲ ptg999 Writing Mobile Websites 7 WatchOut!Testing Is Critical If you plan to create pages and applications for iOS and Android devices as well as desktop browsers, always test your documents in Internet Explorer 8. This browser (and IE 7) still has the lion’s share of the browser market, and if your page or application doesn’t work with it, your page or application won’t work for most people browsing the web. If you don’t have a Windows machine you can use an online tool such as Browsershots (http://browsershots.org/) to test in Inter- net Explorer and other browsers. But what about mobile devices running on Android and iOS, such as a Xoom tablet or iPad? They all come with HTML5 support pretty much out of the box because they each run a browser (Safari on iOS and Chrome on Android) based on WebKit, which has excellent support for HTML5. The best thing about designing web pages and applications using HTML5 for Android and iOS is that what you are creating will work on future devices. Right now operating systems exist that run on tablets and phones and to some extent tele- visions. But these operating systems are moving into other devices such as cars, pic- ture frames, and even refrigerators. Writing Mobile Websites In some ways, writing websites for mobile devices is a lot easier than it used to be. Although a lot more devices are out there, including smartphones and not-so-smart phones, tablets, internet TV devices, and even some picture frames, the devices are converging in what HTML5 features they support, and even in their sizes and shapes (to some extent). When you’re creating a mobile website, the first thing to remember is that a mobile website is just a website. The best websites are built for every browser and operating system, or as many as possible. However, you should still consider some basic questions when building a website that is intended for mobile devices: . What is the screen size and resolution of the mobile device? . What content do your mobile users need? . Is your HTML, CSS, and JavaScript valid and compact? . Should your site have a separate domain for mobile users? . What testing does your mobile site need? ptg999 8 HOUR 1: Improving Mobile Web Application Development with HTML5 WatchOut! What is the Screen Size and Resolution of the Mobile Device When you’re working with mobile devices, obviously the screen size is going to be smaller than on a desktop. In general, with smartphones, you have to prepare for a few standard sizes: . 128 x 160 pixels—Phones such as the Fujitsu DoCoMo F504i . 176 x 220 pixels—Phones such as the HP iPAQ 510 . 240 x 320 pixels—Smartphones such as Blackberry 8100 or the HTC Elf . 320 x 480 pixels—PDAs such as the Garmin-AsusA50 or the Palm Pre Tablets add to the mix by having not only an increased screen size, but also having a variation in how they can be viewed. For example, most tablets (and some smart- phones for that matter) can be viewed in portrait or landscape mode. This means that sometimes you might have a 1024-pixels-wide screen to work with, and other times 800 pixels wide or less. However, in general, the tablets provide a lot more screen space for you to play with on mobile devices. You can assume you have around 1024–1280 pixels by 600–800 pixels for most tablet devices. Browsing most websites in their standard format on an iPad is easy because the brows- er is as clear and easy to use as on a computer monitor. Plus, with the zooming capa- bilities on both iOs and Android, making small, harder-to-read areas bigger is easy. What Content Do Your Mobile Users Need? When you are designing a site for mobile devices, remember that users don’t always want to access the same content as someone browsing on a desktop. For example, mobile customers are often, well, mobile. In other words, they may be in motion or away from their home or office and have a very specific need or desire when they visit your site. For example, when visiting a restaurant website on a mobile phone, a user riding in a car might need to quickly find the location of the restaurant and the phone number. If the mobile site doesn’t have the phone number and location front-and-center, the user might quickly give up on the site. Don’t Limit the Content One thing mobile sites often get wrong is that they remove content from the mobile version of the site. Adjusting the content so that information that is most important to mobile users is easily available is essential. But if the content they need isn’t on the mobile site, you must allow the user the opportunity to look for the content on the full site. ptg999 Writing Mobile Websites 9 Did youKnow? Content for mobile sites shouldn’t be limited, however. In fact, the W3C recommends “...making, as far as is reasonable, the same information and services available to users irrespective of the device they are using.”1 This doesn’t mean that you can’t change the format or location of your content, but getting to the same content on a mobile device as on a computer should be possible. Is Your HTML, CSS, and JavaScript Valid and Compact? You don’t have to worry about writing well-formed XHTML for mobile devices, but sticking to correct, standards-based HTML, CSS, and JavaScript ensures that your pages are visible by the largest number of devices. Plus, by validating your HTML, you will know it is correct. 1 Mobile Web Best Practices. www.w3.org/TR/mobile-bp/#OneWeb. The W3C Validator The W3C has a validator located at http://validator.w3.org/ that you can use to check HTML, XHTML, and other markup languages. But you can also validate CSS and RSS, and even find broken links on your pages from this site. Don’t be afraid to check your site in the validator periodically. You may be surprised at what you find. Beyond writing valid HTML, you should consider avoiding a few things if you are writing web pages for mobile devices: . HTML tables—Avoiding tables as much as you can in mobile layouts is best because of the small size of the screen. Scrolling horizontally is difficult and makes the tables hard to read. . HTML tables for layout—You shouldn’t use HTML tables for layout of web pages in general, but on mobile devices they can make the pages load slow- er and look bad, especially if the table doesn’t fit in the browser window. Plus, when you use tables for layout, you almost always use nested tables, which make the pages load slower and are much more difficult for mobile devices to render. . Pop-up windows—Pop-up windows are often annoying in general, but on mobile devices they can make the site unusable. Some mobile browsers don’t support them and others open them in unexpected ways (often by closing the current window to open a new one). ptg999 10 HOUR 1: Improving Mobile Web Application Development with HTML5 By theWay . Graphics for layout—Like using tables for layout, adding invisible graphics to add spaces and affect layout typically make many older mobile devices choke or display the page incorrectly. Plus, they add to the download time. . Frames and image maps—Many mobile devices don’t support these fea- tures in HTML. In fact, HTML5 no longer includes frames (other than the iframe) as a part of the specification because of the usability issues involved. Fewer Limitations for iOS and Android Although avoiding tables, popup windows, and image maps in mobile pages is best, if you are focusing on mobile pages for iOS or Android, you can rest easy. Both of these handle them without trouble. Frames, however, are not part of HTML5, and you should not rely on their being supported in iOS or Android. Also remember that mobile users often have to pay a fee for their bandwidth, so your web pages should be as small (in KB) as you can make them. The fewer HTML tags and CSS properties you use and server requests you make, the better browsing will be for mobile users. Should Your Site Have a Separate Domain for Mobile Users? Many websites have a separate subdomain for their mobile site. This makes finding the mobile site without having to bother with the regular domain easy for mobile users. These domains are typically something like m.example.com. Having a separate mobile domain offers several advantages: . It makes your mobile site easier to find. . You can advertise the mobile URL separately from the normal URL, giving you more reach. . Having a separate mobile domain enables people on tablets or smart- phones to switch to the full site just by switching domains. . Detecting mobile users and sending them to a separate domain is much easier than scripting changes to your CSS for mobile users. When trying to decide how to handle your mobile site version, consider how you are going to maintain the site. You can create the mobile domain manually with com- pletely separate pages, or you can use a content management system. Hour 4, “Detecting Mobile Devices and HTML5 Support,” covers this topic in more detail. ptg999 Summary 11 What Testing Does Your Mobile Site Need? Be prepared to test your site on as many mobile devices as you possibly can. Although you can use your browser to test or emulate things such as screen size, you won’t see some of the horrible things that can go wrong if you don’t test on mobile devices directly, such as the following: . Packet size limitations by mobile carriers preventing your page or images from loading . Images loading incorrectly or not at all . Inability to scroll horizontally (which is nearly impossible to do on some phones) . Device-specific features not working that you were relying on . File formats not being supported You likely don’t have an unlimited budget for buying mobile phones (and their associated cellphone plans), so what do you do? Here are some suggestions: . Use emulators—Both online and offline emulators are available for many different mobile devices. Most are free to use and they give you at least a start at testing your site for mobile devices. . Rent time on devices—Services exist that will allow you to rent time on multiple phones. You can justify the cost by getting a sense of how the phones handle your applications. . Buy some phones—This might seem like an expensive option, but if you are planning on doing a lot of mobile web development, it could be a rea- sonable investment. . Get help from friends and co-workers—This is one of the least expensive ways to test your site—simply ask to borrow phones or tablets from people you know. You just need to put your site on a live web server. Ultimately, if you are going to do mobile development, you should have at least one mobile device you can test your pages on directly. The more devices you can test on, the better your sites will be. Summary In this hour, you have learned how HTML started and the reasons for the move from HTML to XHTML to HTML5. You know the basic differences between HTML 4, ptg999 12 HOUR 1: Improving Mobile Web Application Development with HTML5 XHTML 1, and HTML5 as well as what web applications are and how they relate to the Open Web Standard. You learned how to write a basic HTML web page and why HTML5 fits in so well with mobile devices. You also learned some powerful tips for building mobile web pages. The most important things to remember from this hour are the best practices for building a website for mobile users: . Focus first on building a website or application for every user, not just mobile ones. . Determine who your mobile users are and what they are looking for, and present that content to them first, but not only that content. . Build a site that uses standards-based technology so that your applications are more future proofed. . Always test your sites and applications in as many web browsers and devices as you can. Q&A Q. I am not familiar with HTML, and I’m worried that I will have trouble building an HTML5 application. Do I need to know HTML 4 before I learn HTML5? A. Although knowing HTML 4 will make moving forward easier for you, learning HTML5 is a fairly straightforward process. Although this book focuses mostly on HTML5, by copying the code samples provided and looking at the source files for the companion website (www.html5in24hours.com/), you should be able to figure it out. Q. I already have a website, and I want to make sure that mobile users can get the most out of it. How do I make sure that I am providing what mobile users need? A. The best way to do this is to ask them. Surveys asking your customers how they access your site and what parts are most useful to them are a good indicator of what they want. But you can also look at your web statistics. If you don’t have analytics on your website, I recommend installing one such as Google Analyt- ics or Piwik to track what people are looking at on your site. After you know what the popular pages are, you can ensure those pages are easy to access in your mobile version. You can also use your web analytics to see what browsers (Firefox, IE, Chrome, etc.) are visiting your website and how your customers use the site (pages they ptg999 Workshop 13 click on, where they leave, and so on). With this method, even if you can’t get direct customer feedback you can see what features they are currently using and adjust your site accordingly. Q. You mentioned using a content management system for maintaining a mobile site. Do you have any you can recommend? A. I use WordPress with the WordPress Mobile Pack to maintain a lot of sites for mobile and non-mobile users. Workshop The workshop contains quiz questions to help you process what you’ve learned in this chapter. Try to answer all the questions before you read the answers. See Appendix A, “Answers to Quizzes,” for answers. Quiz 1. Who decided to initiate HTML5 and why? 2. What is the first line in an HTML5 document? 3. Why is HTML5 so well suited to mobile application development? Exercises 1. Create an HTML5 page. Your page should have a title, headline, and at least two or three paragraphs of text in it as well as the HTML5 doctype. Hour 3, “Styling Mobile Pages with CSS3,” covers more about how to use CSS for styling the layout and look of your page. 2. Start planning your mobile website. List the content that you have that is par- ticularly well suited to mobile users. List the content you need to create for mobile and non-mobile users. Ask yourself whether you have the resources to maintain a completely separate mobile site or whether you are going to use a content management system to maintain it. ptg999 This page intentionally left blank ptg999 The New HTML5 Tags 15 HOUR 2 New HTML5 Tags and Attributes with Mobile Development What You’ll Learn in This Hour: . How to use the many new tags and attributes in HTML5 . Other changes in HTML5 . Mobile support for HTML5 . Reasons to use HTML5 for mobile web applications HTML5 has many new tags and attributes that you can use for building web pages and applications. In this hour you will learn about many of the new HTML5 fea- tures and how they work on mobile devices. The new smartphones and tablets are driving the adoption of HTML5, and this chapter tells you what you can do to be a part of the revolution. The New HTML5 Tags HTML5 adds a lot of new features to the HTML specification, but the easiest ones to understand are the brand-new tags. These are HTML elements that have never been a part of HTML in the past. New Layout Tags Most of these new tags are called “sectioning” elements and they provide semantics for the layout and sections of an HTML document. Hour 9, “Adding Meaning with HTML5 Sectioning and Semantic Elements,” covers these tags in more detail. ptg999 ▼ 16 HOUR 2: New HTML5 Tags and Attributes with Mobile Development These tags are: .

—An independent portion of the document or site. .