[...]... 336 10.1 Combating latency 338 Countering latency with feedback 338 Showing progress 345 Timing out Ajax requests 351 Dealing with multiple clicks 355 ■ ■ CONTENTS 10.2 Preventing and detecting entry errors 359 Displaying proactive contextual help form entries 366 10.3 11 ■ Validating Maintaining focus and layering order 374 Maintaining focus order 10.4 359 Summary 375 ■ Managing stacking order 381... chapters in part 2, Ajax Best Practices,” present various practical topics in client-side programming, with an emphasis on using Ajax directly, or on practices and principles that work well in Ajax- enabled applications Chapter 1 dives head first into what makes Ajax different from other technologies and why there’s so much to be written (and learned) about it It presents a crash course in using Ajax across... http://www .manning. com/crane2 or http://www .manning. com/AjaxinPractice Author Online Purchase of Ajax in Practice includes free access to a private web forum run by Manning Publications where you can make comments about the book, ask technical questions, and receive help from the authors and from other users To access the xxii ABOUT THIS BOOK forum and subscribe to it, point your web browser to http://www .manning. com/... Fundamentals of Ajax toolkit, and jQuery, an exciting (relative) newcomer to the Ajax arena The chapter concludes with a look at how DWR uses Ajax to provide an approximation of RPC (remote procedure calling) using Ajax as a transport mechanism Embracing Ajax This chapter covers ■ What makes Ajax different ■ Basic usage of XMLHttpRequest ■ Simplifying Ajax using libraries 3 4 CHAPTER 1 Embracing Ajax Ajax has... discuss in the next section Figure 1.2 Work-work pattern of interaction in an Ajax application Ajax as a disruptive technology 7 1.1.2 Redefining web application architecture Web application architecture has always been an interesting field Because of the challenge of maintaining an adequate user workflow in the face of the work-wait nature of the Web, there has been a continual stream of innovation in. .. applications is not a well-defined, solved problem, and that plenty of room still exists for innovation Ajax disrupts the web architecture landscape by moving the innovation in new directions, not by providing a single solution Think of figure 1.3 as presenting three points along a spectrum, with Ajax- enhanced legacy applications tending to sit near the middle, and line-of-business Ajax apps toward the right-hand... 272 Capturing keyboard shortcuts 274 Disabling the right-click context menu 275 Preventing users from navigating history or refreshing 276 ■ ■ ■ 8.2 Working with a browser’s navigation controls 280 Using the JavaScript history object 280 Hashes as bookmarks 281 Introducing the Really Simple History (RSH) framework 283 Using RSH to maintain state at the client level 284 Using RSH to maintain state at... approach to Ajax, but we are making them think again, and picking up some new skills along the way As we get deeper into Ajax and move toward the new breed of line-of-business web apps that Ajax has enabled—the scope for changing the architectural tiers increases On the right-hand side of figure 1.3, we’ve depicted an extreme case of an Ajax- based application, in which the JavaScript code in the browser... does Ajax affect my application architecture?, and even, What does Ajax mean for my business model? Collectively, the development community has embraced Ajax and, as with the best inventions, used it in new and interesting ways Google demonstrated that, using Ajax, “solved problems” like online maps and webmail still had plenty of room for radical innovation The recent interest in “mash-ups” (the mixing... than one website in a single page) has a natural affinity with Ajax, too Along the way, we’ve amassed practical experience in using Ajax in real-world applications and settings Our purpose in writing this book is to capture some of this practical experience with Ajax, and go beyond the basic proof-of-concept code to look at what does—and doesn’t—work in the real world As such, we intend to focus on . FUNDAMENTALS OF AJAX 1 1 Embracing Ajax 3 1.1 Ajax as a disruptive technology 4 Redefining the user’s workflow 5 ■ Redefining web application architecture 7 1.2 Ajax in ten minutes 9 Introducing XMLHttpRequest. Validating form entries 366 10.3 Maintaining focus and layering order 374 Maintaining focus order 375 ■ Managing stacking order 381 10.4 Summary 387 11 State management and caching 388 11.1. chapters in part 2, Ajax Best Practices,” present various practical topics in cli- ent-side programming, with an emphasis on using Ajax directly, or on practices and principles that work well in Ajax- enabled