Re: pseudo-attributes

On Thu, Oct 16, 2008 at 12:57 PM, Daniel Glazman <
daniel.glazman@disruptive-innovations.com> wrote:

>
> L. David Baron wrote:
>
>> Here's an idea for a future level of selectors, which I proposed a
>> few days ago in
>>
>> http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2008-October/016544.html
>>
>>
>> There are some things, like the values of form controls such as text
>> inputs, that are rather like attributes (in that they have string
>> values), except they're not actually attributes in the markup.  The
>> various forms of attribute selectors would all make sense on these
>> things.
>>
>> The one I'm suggesting here would be a :value pseudo-attribute,
>> representing the current value of a text control.  (The value
>> attribute in HTML represents the default value, not the current
>> value.)
>>
>> With this, one could, for example, style inputs that don't have
>> anything in them:
>>
>>  input.mandatory[:value=""] { background: red; }
>>
>
> In fact the initial value of the input is rarely blank:
>
>  Please insert your family name below:
>  +-----------------------------------+
>  | Your family name                  |
>  +-----------------------------------+
>
> Localizing this would be difficult because you would need a
> style rule per localization. Another way to do that could be
> a pseudo-class comparing the actual value of the element with
> the value of the attribute (or the textual content in some
> cases) holding the initial value of the form element.
>

Using @value for hints, though relatively common due to the easy of it, is
not a good practice, semantically or user-friendly-ly (just think about how
this works on mobile browsers...).  You need to clear it out when they start
typing with javascript, it's not actually a valid value if the user
contrives to submit it with that value, etc.  There was some discussion just
a week or two ago on the whatwg about a @hint attribute on <input
type="text"> and <textarea> that would display text as long as the control
was empty and not focused, and this value would never be submitted.

@David Baron:
The hint action can be done just as well with :empty:not(:focus).  Is there
a reasonable use-case that :empty doesn't solve equally well?

~TJ