Matching of implicit 'value' attributes has changed

[mikecapp]

​http://jsfiddle.net/mikecapp/rjyRx/

We had a

filter("[value=]")

applied to an input element, where the empty 'value' attr being tested for was often implicit. This worked in all tested browsers in 1.4.2. It doesn't work in FF/Chrome in 1.6.2, or as far back as 1.4.4. (Don't know about 1.4.3; jsfiddle doesn't offer it.) It still works in IE7/8, or if the empty value is explicit.

(I wouldn't say this is a regression per se, since I suspect we were accidentally relying on undefined behaviour. But it broke our app, so I thought I'd flag it in case anyone has a "whoops, didn't mean to do that" moment.)

[mikecapp]

Implicit values in 1.4.4+ don't work in IE9 either

[addyosmani]

Confirmed, however I'm not entirely sure this behaviour has been defined or documented so it's difficult to say whether we really want to support this. I can't imagine many cases where others may wish to use filter("[value=]"), but CC'ing dmethvin for a second opinion.

[mikecapp]

Filtering for an empty value is definitely useful - we do it in several places, for different reasons. It's the *implicit* value that I suspect puts this in the realm of undefined behaviour.

[dmethvin]

Definitely need quotes there, so it was just a coincidence it worked before.

[mikecapp]

Quotes are irrelevant - changing the filter to [value=""] produces exactly the same results. The explicit/implicit distinction in this issue is about the presence/absence of a value attribute in the markup.

[timmywil]

QSA retrieves the attribute, but IE6/7 retrieves the property. This will be consistent when the value attrHook is removed (meaning it will work the way it does in Chrome/FF).

[dmethvin]

Sorry, I misunderstood the original issue. However, I don't think the hook is going to fix the real problem, is it? That is, <input /> does not match input[type="text"] or input[type] or input[type=""] because querySelectorAll requires an explicit attribute:

​http://jsfiddle.net/uEyhf/4/

[timmywil]

I don't think that's related here. The behavior of Sizzle will match QSA for the value attribute when the value attrHook is removed. type has other issues.

[timmywil]

Duplicate of #9830.