Preface
Ajax: It is part revolution, part evolution, and some would say all hype. Ajax is an umbrella term used to encompass a set of technologies including:
Markup, such as HTML, XHTML, XML, and SVG
JavaScript
CSS and XSLT
Last but not least, browser objects, including the
canvasobject and the object that really makes Ajax,XMLHttpRequest
Despite all of the recent interest, most of these technologies have been around for about a decade. Why the interest now?
Ajax is more than just a set of technologies—it's also a determination to take web pages and applications in new directions. We've had this determination in the past, but we never had the tools with which to build these applications. Now, the specifications that were all new ten years ago have reached maturity, and, even more importantly, have broad support in web browsers. New specifications continue to appear, and tool makers cooperate much more than they did a few years ago.
Years ago when web developers made first tentative motions to add interactivity to web pages, we were constrained by browsers that supported completely different models, and at times, even different scripting languages. The use of Cascading Style Sheets (CSS) as a uniform way of adding presentation to a page was hampered by differing interpretations, not to mention proprietary extensions.
Now, CSS has almost universal support, and though there are still "quirks" in the system, most browsers support most of the specifications, and we're at a stage where what ...