Aria-live regions will help a screen reader user get the dynamic updates on the application without losing the current focus from the activity that is being performed. Aria-live property is extremely useful to make a screen reader user under stand the complex widgets like dynamically updating tables or chat windows etc and the aria live property can be useful for regularly updating news sites, blogs & applications that pull data from social channels, gamification portals etc.
The aria-live property indicates a section within the content that is live and the verbosity in which changes shall be announced. The following values may be used to determine the verbosity,
Aria-live=”off” indicates that a region is not live & changes will not be announced to the user. This attribute is used when there is a frequently updating content for example tweets & facebook activity that is being pulled into the site. There is no necessity for the user to get these updates by default, how ever user can read these updates by usual navigation.
The update must be announced at the next interval. For example when the user stops typing or when the user is waiting for an update to happen & the most important thing to note is that user will not be interrupted by the live region in order to provide the update.
Example breaking news headlines, new offers in ecommerce stores, optin box for blogs etc.
Aria-live=”assertive” will inform the update immediately & this must be used with care as update is announced mmediately this cannot be used in a live region where frequent updates are expected.
For example aria-live=”assertive” can be used for form validation, appearance of new chat windows and one time offer of a product in ecommerce stores.
More examples of Aria live property can be found on the following websites,
Here is a screen capture video explaining all about ARIA live regions & this video is little behind the time, but concept is valid.
Note: I am just sharing the knowledge that I acquired by reading & practicing as accessibility consultant. Lot of this is already available on the web & is sharing it here on my blog so as to make my self an expert in the field & to remember the concepts.