2. Ensure that dynamic content can be read by a screen reader without deviating from "normal" modes of page navigation and that visually hidden content can be read by a screen reader
The term "AJAX" is commonly used to refer to web page content that is updated without a screen refresh. (The term actually refers to the activity of injecting into a page content from a remote web resource, database, or external web page.) When such dynamic changes occur and page content that is not currently focused by the screen reader updates, how will the screen reader user be informed of the change? How will we draw his/her attention to the updated content? And, even if we can draw attention to it, how can we be certain that her screen reader will have an updated representation of this new content and not simply read back the outdated content that was stored in his/her screen reader's cache of the page? The unfortunate answer is that we cannot be certain. There are emerging standards for coding web pages that can help guarantee that screen readers are aware of dynamic changes to page content, but acceptance and implementation of these standards varies from AT to AT and from browser to browser. While it is certainly important to be apprised of emerging specifications whose goal is to make rich internet content accessible, such as the W3C's ARIA specification (see Resources for this section of the best practices), the only truly valid means for ensuring that updated content can be read is by testing with AT and, preferably, doing user tests. The point to take away from this Best Practice and this section of the document, in general, is that while there are clear and reliable techniques for ensuring accessibility when we are implementing static HTML pages, dynamic pages require on the part of the content developer and designer creative thinking, heightened awareness of accessibility issues, and willingness to perform rigorous evaluations.
4. If you manipulate the cursor focus or otherwise update the student's position within a web page, only do so when she expects such actions to occur
- Web Accessibility: Web Standards and Regulatory Compliance — By John Paul Mueller, read especially Part Two of that book
- WAI-ARIA Introduction — Making Ajax and Related Technologies Accessible
- CodeTalks — Best one-stop information and discussion