Like vintage bowling shirts and wearing your pajamas to school, asynchronous JavaScript with XML, a.k.a. Ajax, seems to have begun as a West Coast fad. But it’s quickly gaining acceptance worldwide as developers look to design Web interfaces that hook users with their speed and ease of use.

But while clothing trends come and go, Ajax looks like it may stick around, offering Web developers a means to create rich clientlike applications on webpages without resorting to huge amounts of code or forcing users to download plug-ins. However, like every hot new Web technology, CIOs must hold firm against the regular barrage of "if Google is doing it, why can’t we?" and find the underlying value in Ajax for their particular companies.

Where Ajax Came From

Freely draggable satellite images on Google maps. Instant spellchecking in Gmail. They’re cool features. Admit it. The launch of tools such as those revitalized interest in both the online mapping and Web-mail markets. With a flourish, Google demonstrated that browser-based applications could support rich clientlike capabilities and performance—without the rich client.

The secret sauce was a clever combination of JavaScript and XML. XML-based data could be pre-downloaded into the user’s browser where JavaScript code could quickly perform operations on it—sorting a list of products or e-mail on the fly, for instance, or letting you drag map images around the screen—without the tedious back and forth between browser and server.

The idea was not new: Developers have been using JavaScript and locally cached data to offer rich interfaces since the ’90s. But the stars had not yet aligned. Most users still connected to the Internet via dial-up connections, making background data downloads tricky. Browser compatibility with JavaScript was hit or miss. And limited processing power on client PCs could throttle the performance of all but the most simple JavaScript applications.

Over time, JavaScript began to fall out of vogue in favor of server-side scripting—which guaranteed compatibility across browsers—and client-side development tools such as Macromedia’s Flash, which provided a clear path to rich applications even if it did require a browser plug-in to operate.

But in the past 18 months, JavaScript has seen a resurgence, driven by the likes of Google, Yahoo and even Microsoft. Just as important was the coining of a short, memorable and highly marketable term for the collection of technologies currently behind many of the most well-known applications. In a Feb. 18, 2005, blog entry by Jesse James Garrett, cofounder of user-experience consultancy AdaptivePath, asynchronous JavaScript and XML got a name: Ajax.