There's one key question to consider when planning the development of a website and the use of AJAX: Is there a real need to use AJAX?. If the answer is yes, then ensure the following is true to ensure AJAX accessibility is optimised:
Inform users early in the page that dynamic updates will occur Not all users are familiar with AJAX
interfaces. Let them know that changes may take place so they can
expect and look for these changes. This is particularly important for
screen reader and magnifier users as they may be unaware that changes
have taken place.
Highlight the areas that have been updated Using
subtle changes to highlight areas that have changed, for just a short
period of time, can be most helpful. It will inform users, in
particular those with reading difficulties that updates have taken
place.
Don't change the focus Do not move
the focus of the page to where the change has taken place. Changing the
focus can be disrupting for screen reader and magnifier users
especially if there are no mechanisms to return to the previous
position.
Offer the option to disable automatic updates Allow
users to manually request page updates, for example by providing links
and/or form buttons to refresh the page on-demand. Screen reader and
magnifier users may be unaware of on-the-page changes. It can also be
difficult for users with reading difficulties to keep up with automatic
updates. If possible, store users' preferences for requesting page
updates for future visits to the site.
Ensure the site works if JavaScript isn't enabled Build a standard application then overlay it with AJAX to improve its functionality. If JavaScript is disabled or not available then users will still be able to use the site.
In case of an advanced AJAX application, consider providing an HTML alternative. If the AJAX
application is impossible to use by group of users (e.g. if it relies
on the use of a mouse, such as the drag & drop sliders) then a link
to an HTML alternative is a must.
