1. If error message were mapped to description in a11y APIs, the user
agent can choose to expose it first and only when aria-invalid is true.
2. aria-invalid communicates the state of "urgency". For example, NVDA
says "invalid entry". I don't think screen readers should provide an
additional indication for an error message, as that would be redundant,
but that's an implementation detail, not a spec detail.
3. It occurred to me that one possible annoyance with error message
being mapped to description is that if both were present, a change in
one might cause both to be read.
4. We might be able to mitigate the performance concern using the
invalid state; i.e. we only need to check for error message if invalid
is set. Joanie, thoughts?
Jamie
On 14/04/2016 7:01 AM, Joseph Scheuhammer wrote:
On 2016-04-13 11:46 AM, Matt King wrote:
When aria-errormessage was first discussed, my understanding was that the
purpose is to distinguish an error message from a description so that assistive
technologies would have the option to give it special treatment.
Is there more to it than that?
Aria-errormessage is tied to aria-invalid. The error message is
relevant only when the input is invalid. In contrast, descriptions have
no specific dependency on validity.
Based on that, the error message is presented only when the input is
invalid. For a sighted user, the error message is not rendered unless
or until the user has input invalid information. At that point the
error message is shown near or "attached" to the invalid input. If the
user corrects the input, the error message vanishes, thereby providing
reinforcement that the error has been corrected. On the other hand, the
description is presented on demand -- for example, as a tooltip when the
user mouses over the control. A corollary is that the error message
conveys a sense of urgency or obligation -- something needs to be fixed
-- whereas the description does not.
--
James Teh
Executive Director, NV Access Limited
Ph +61 7 3149 3306
www.nvaccess.org
Facebook: http://www.facebook.com/NVAccess
Twitter: @NVAccess
SIP: [email protected]
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