W3C home > Mailing lists > Public > public-html@w3.org > March 2013

Re: Proposal: Provide better advice on constraint validation instructions

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Thu, 14 Mar 2013 00:33:55 +0100
To: Steve Faulkner <faulkner.steve@gmail.com>
Cc: HTMLWG WG <public-html@w3.org>
Message-ID: <20130314003355646983.6180c28d@xn--mlform-iua.no>
Steve Faulkner, Wed, 13 Mar 2013 11:13:59 +0000:

> OS X 10.7 in Safari the content of an element referenced using describedby
> is mapped to the AXhelp property. (this can be checked using the mac
> accessibility inspection tool.

If AX inspector is needed, then where s the better advice ... ?

> Voiceover announces the content of AXhelp after a use configurable delay.

Your aria-describedby example fails in released Safari+VoiceOver, in OX 
10.7 and 10.8. But it does work in Webkit Nightly and in iCab. If your 
aria-describedby solution worked, then the description would have 
gotten repeated - such is at least VoiceOver’s behavior. To avoid that 
problem, the instruction element can be hidden with aria-hidden="true". 
(You could hide with @hidden as instead, but the keyboard users would 
be out of luck if for instance CSS was disabled - which seems counter 
to your motivation for fixing the spec.) 

BT: To verify whether you experience aria-describedby or just source
order, you can add a line of text between label and the #instructions:

<label>Part number:<input … aria-describedby="instructions"></label>
 —> <p>Text in between.</p> <—
<p id="instructions"> A part number  …</p>

> If aria-labelledby is used one has to reference both the label and the
> description, it is a possible alternative but is more complex.

First: Didn't know. Sounds like a good point - as long as the total 
solution works. For me it doesn't. 

>> If one get it to work - arial-labelledby or aria-describedby, then,
>> unless one takes special care to hide the instruction when <input> does
>> not have focus, the instructions are read twice - once together with
>> <input> and once "alone". (Based on VoiceOver) 
> 
> the typical scenario is that users are moving from control to control in a
> form.

So? If the aria-describebedby referenced text is read, then it should 
be read before AT gives the user a que to start writing - and not after 
that que. 

>> (4) In Safari+VoiceOver, the following would would work - and it has
>> the advantage that @tite remains were it was: 
> 
> I think this is an overly complex solution it may be appropriate in a
> tutorial (if it works as you say), but the use of aria-hidden and CSS
> generated content and ARIA roles, makes it more prone to cross
> browser/cross OS issues, so it is not something that I would suggest
> putting in the spec.

I have simplified. Following example uses 2 + 1 aria attributes, and 
don't need CSS. (The '+ 1' is the space filled aria-label hack, which 
has as similar effect on current release of Safari as a non-empty @alt 
attribute on <img> - it causes the browser to not ignore the input 
element. You perhaps don't need to show that hack in the spec - it 
seems unnecessary in the Webkit nightly.)

<label>Part number:
    <input pattern="[0-9][A-Z]{3}" name="part" aria-label="  " />
    <span aria-hidden="true" >The part number is a digit followed
    by three uppercase letters.</span>
</label>

Note again that that aria-hidden="true" is there in order to solve the 
problem of the repeated instruction text. Not as well that you could 
instead have used the @hidden attribute. But not that the the element 
then would remain hidden form keyboard only uses if in CSS-disabled 
browers. If you delete the aria-hidden="true", then users will get text 
repeat instead.

Have not tested in Jaws or NVDA due to the amount of work that would 
involve right not.
-- 
leif halvard silli
Received on Wednesday, 13 March 2013 23:34:25 UTC

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