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Introducing Ajax

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This chapter starts with a brief introduction to Ajax and then offers three simple examples of how Ajax can be implemented.
This chapter is from the book

A little more than a year ago, an article by Jesse James Garrett was published describing an advanced web development technique that, even though individual components of it have existed for years, few web developers had ever stumbled across. I can guess the reason for this lack of knowledge; basically, in the last few years, the need to produce measurable results has gotten in the way of the need to practice our craft. Or, as a former manager of mine would say, it's "that mad scientist stuff," except, as I recall, he used another word in place of stuff. Unfortunately, nine times out of ten, the need to produce measurable results gets in the way of "that mad scientist stuff."

However, it's the tenth time that's important. The article didn't stop at just describing the technique; it went on to say that Google used the very same technique. Invoking that single name, Google, was enough to change a point of view. Quicker than you could say, "Igor, the kites!" the phrase "that mad scientist stuff" morphed into "Why aren't we doing it this way?" The reason for this change of perception is that the name Google made this a technique that could produce measurable results. All it took was that single name, Google, to make using the XMLHttpRequest object so that the browser could communicate with the server without the page ever unloading and reloading into an acceptable practice.

This chapter introduces you to that practice, the practice of updating web pages with information from the server. Beyond the XMLHttpRequest object, which has been around for several years as a solution looking for a problem, there is nothing weird needed. Basically, it is how the individual pieces are put together. When they're put together in one way, it is nothing more than a pile of parts; however, when put together in another way, the monster essentially rises from its slab.

2.1 Not a Mockup

A few years ago, I demonstrated an application that did what I just described. The demo ran for more than 2 hours with the same questions repeated over and over.

"It's a mockup, right?"

"No, it is the actual application."

"It can't be. The screen doesn't blink."

"That's because XML, HTTP, and SOAP are used to get the data directly from the server. JavaScript then updates only the parts of the page that have changed."

"It's a mockup, right?"

And so on. It took the client more than 2 hours to realize that the database was actually being updated without the page "blinking," as he referred to it.

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