In addition, until a few years ago, processors ran too slowly for JavaScript. Even if the physics had worked, until recently the same code couldn't have run on all Web browsers, Bosworth says.
Finally, or perhaps most important, in Bosworth's estimation, personal applications like Google Maps and Gmail were in the minority of Web applications and were in less widespread use five or six years ago than they are today.
Some Limits
Not all applications may be right for the AJAX approach. Skeptics frequently cite "breaking the Back button" as a serious problem. Because AJAX allows Web pages to be modified locally and/or incrementally, clicking on the Back button doesn't necessarily return a user to the previous page. The Back button may take the user all the way back to the beginning of a long interaction—the one specified by the URL shown at the top of the Web page.
For the same reason, the URL at the top of the Web page doesn't completely specify the contents of a page, so it may be impossible to bookmark desired pages or share URLs so that others may see the same Web content. And asynchronous updates, as blogger Alex Bosworth (son of Adam Bosworth) and others have pointed out, mean that a Web page could adjust its shape, layout or length unexpectedly.
Despite those drawbacks, AJAX has generated real excitement with its promise of more-responsive Web interactions. Garrett ends his essay with this Utopian vision: "The biggest challenges in creating Ajax applications are not technical. ... The challenges are for the designers of these applications: to forget what we think we know about the limitations of the Web, and begin to imagine a wider, richer range of possibilities."
Matlis is a freelance writer in Newton, Mass. He can be reached at jmtgpcmcm@aol.com.
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