Notifications and alerts of content changes, errors, and status updates are important aspects of a website or web application’s usability. For example, a notification that provides feedback on an incorrect or malformed input to a form can help speed up the task of error recovery, while a notification of an impending timeout can help users take action to avoid being inadvertently logged out.
Often, though, notifications can be missed by screen reader users, if the notification is not implemented in a way that a screen reader can detect it, for example, by appearing earlier in the content order than where the screen reader is currently reading. People with impaired vision may also miss an update, for example, if the visual change is subtle, or if the screen is magnified and the update appears in an area of the screen that is not in the current viewport.
Take care to ensure that notifications and alerts are provided for important events, and that they are provided in an accessible way so that people with disabilities can access them and respond if necessary.