There’s a craze on the web at the moment, and that craze is named AJAX. What’s that? Well, according to some people, it’s a technology that’s going to redefine the web.
What Does AJAX Stand For?
AJAX means ‘Asynchronous Javascript and XML’. Adaptive Path came up with the term in this essay: http://www.adaptivepath.com/publications/essays/archives/000385.php. However, the word is really a bit of a misnomer: AJAX doesn’t really rely on XML at all, but rather on a Javascript function that happens to be named XMLHttpRequest.
All About XMLHttpRequest.
XMLHttpRequest was originally invented and implemented by a Microsoft team who were working on a webmail application, and it’s been around for a while now (since 1999, in fact). The reason it has suddenly come to prominence now is that Google used it in three projects, Gmail, Google Suggest and Google Maps, and in each case managed to create a much better user interface than they would have been able to otherwise.
So what does XMLHttpRequest do? To put it simply, it lets your Javascript go back to the server, fetch some new content, and write it back out onto the page – all without the user having to change pages. This gives a ’smoother’ feel to web applications, as they can do things like submit forms without the whole browser window needing to go blank and reload the page. Take a look at maps.google.com now, and notice how you can drag the map around anywhere you want to go without having to reload the page. This would be unthinkable without XMLHttpRequest…
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