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>

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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