AJAX, or Asynchronous JavaScript and XML, was probably the most-hyped web programming technique in the last two years. It’s no surprise, as it enables you to do a lot that couldn’t have been done just a few years ago.
AJAX is being used in more and more places, often when it doesn’t need to be…and when it shouldn’t. With all the talk about how you can use AJAX for everything, the real question is when should you.
You should use AJAX in places where it will improve the user experience. One example is with polls. Why should a full pageload be required just to vote in a poll (or view the results)? That’s a waste of your users’ time, and a waste of your server resources.
Do not use AJAX for loading your main content, though. It’s not a good idea. I’ve seen a few sites that have tried it, and it doesn’t work that well. You have to come up with extra solutions for search engines, because they can’t understand your JavaScript trickery (you thought the dreaded “text-only version” link only applied to Flash sites? ). You also cause problems for people using some browsers (Safari, IE5, etc).
Basically, you want to use AJAX for things where an extra pageload would be irritate the heck out of everyone. Suppose you have a star-rating system, like on Netflix. Wouldn’t it be horrible if you had to sit through a page refresh every time you rated a movie? Use your own judgment.
