AJAX/AHAH/DHTML

What is this alphabet soup all about?

AJAX is an overused term. Technically it refers only to asynchronous JavaScript and XML. "AHAH" (pronounced like "a-ha!") is asynchronous HTTP and HTML. If you care what this mess of nested acronyms and abbreviations means, it's just interactive stuff that you can play with without having to go through another whole pageload. So you can fill out forms without hitting submit. That kind of thing.

Of course there are other ways to get the page to do things without a new pageload. There's plain old JavaScript, without any extra letters, and you can do fun things with CSS because it recognizes things like when the mouse is over a certain part of the page. Lots of people call everything that you can do without a new pageload "AJAX". I'm going to refer to it by the more politically correct name DHTML, which basically means HTML that does some fancy stuff.

How on earth do you accessify all that?

So what are the accessibility considerations for all these various applications? You might think that's a complicated question to answer. After all, collapsible fields are vastly different from Flickr's imagestream and WYSIWYG editors. But the specific issues involved in each case can all be addressed by answering one question:

Does it degrade gracefully?

Graceful degradation is vitally important to progressive enhancement on the Web. Remember that progressive enhancement dictates that we must never allow an advance in one user's experience to come at the expense of the quality of another user's experience. Graceful degradation is also the main desired consequence of a good separation between content, structure, and presentation. And it's increasingly important as Web applications and websites grow more and more layers and functions and frills.