AJAX and DHTML have made web sites more interactive and easier to use. At least for visitors who are not using a screen reader. Screen reader users have to struggle with pages that lose focus, change without prompting the user of new data, and much more. However, there are many developers working on solutions to this problem.
Here’s how Todd describes the goal
The YUI TabView Control is built on a strong
foundation of semantic markup that provides users with some basic accessibility. But while TabView looks like a desktop tab control, screen readers don’t present it as an atomic
widget, leaving users to figure out how the various HTML elements that compose a TabView relate to each other. However, through the application of the WAI-ARIA Roles and States, it is possible to enhance TabView’s accessibility such that users of screen readers perceive it as a desktop tab control.
The following video shows how this approach works with Firefox and a screen reader.