[whatwg] :invalid

Mounir Lamouri mounir.lamouri at gmail.com
Fri Dec 31 02:28:41 PST 2010

On 12/31/2010 02:13 AM, Ian Hickson wrote:
> On Thu, 23 Sep 2010, Mounir Lamouri wrote:
>> The current specification of :invalid is pretty simple: it matches all 
>> invalid elements which are candidate for constraint validation.
>> Today, Gecko betas, Presto and Webkit support :invalid (I didn't check 
>> for IE). Unfortunately, :invalid is far from being perfect and most 
>> UI/UX guys would tell you that the current :invalid behavior is really 
>> bad. For example, having the invalid style applying as soon as you load 
>> the page (ie. for <input required>) is not a good thing. There are few 
>> UX rules like that that :invalid currently breaks.
>> So, to improve the user experience while using web forms we would like 
>> to fix that. However, we are wondering if :invalid (and :valid?) 
>> specifications should be updated to take UX considerations or if a new 
>> pseudo-classe should be created. Does anyone has an opinion about that?
>    <form onblur="event.target.classList.add('examined')"
>          onsubmit="for (var i = 0; i < elements.length; i += 1)
>                      elements[i].classList.add('examined')">
> ...along with CSS rules like:
>    .examined:invalid { ... }
>    .examined:out-of-range { ... }

Since then, we have implemented something you can try with Firefox
4.0b8: :-moz-ui-invalid and :-moz-ui-valid. By default, all element
matching :-moz-ui-invalid have a red box shadow.

The rules for :-moz-ui-invalid are the following:
a. When not focused (AND list)
 1. The element has its default value changed OR the element is in a
form that the user tried to submit (but was invalid) ;
 2. The element is invalid (:invalid applies).
b. When focused (OR list):
 1. If the element had :-moz-ui-invalid before it was focused,
:-moz-ui-invalid applies if the element is invalid (IOW, if the element
was valid or no style was applying, the element will not be shown as
invalid as long as the user do not blur the elemnet) ;
 2. Otherwise, :-moz-ui-invalid will not apply as long as the element is

:-moz-ui-valid is very similar to that.
Note that we chose to have none of these pseudo-classes applying if the
form has novalidate attribute and :-moz-ui-invalid always apply if
.setCustomValidity() has been used to make the element invalid.

My description is probably not really clear because the UI rules are
somewhat complicated but we hope this give a nice user experience.

We would welcome any feedback about these new pseudo-classes.

> On Thu, 23 Sep 2010, Boris Zbarsky wrote:
>> Are there cases when pages would set invalid default values and want 
>> them flagged as such in UI?
> On Fri, 24 Sep 2010, Shiv Kumar wrote:
>> Typically, in large organizations, there are folks who clean up data. So 
>> they will be presented with data that's already entered by someone else 
>> and their job is to clean up the data. In fact I see the new Form API to 
>> be a very good candidate for this use case.
> Indeed.

Our implementation lets you use :invalid for such use case.


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