Intent to implement and ship: spec changes to the .form property and "form" attribute on <label> elements

[Boris Zbarsky]

Summary: The "form" content attribute on <label> elements no longer
means anything. .form returns the .form of the labeled control, or null
if nothing is labeled or the labeled thing has no .form. In particular,
you can no longer associate a label with one form but associate its
labeled control with a different form.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1268852

Spec: https://github.com/whatwg/html/pull/1120 and
https://html.spec.whatwg.org/multipage/forms.html#the-label-element and
https://html.spec.whatwg.org/multipage/forms.html#dom-label-form

Estimated release: 49

devtools bug: none needed, I think.

Support in other browsers: Chrome is planning to do this. See
<https://groups.google.com/a/chromium.org/d/msg/blink-dev/QWyCpJjgfY8/TOxG9n-OAQAJ>.
According to that message, Edge and WebKit don't support the "form"
content attribute on <label> anyway; .form always returns the ancestor
form in those engines.

-Boris

[smaug]

As I said in https://github.com/whatwg/html/issues/787 this change looks ok to me.


-Olli

[Florin Mezei]

Is there any chance for this to break web compatibility? Sounds like it
shouldn't.

Regards,
Florin.

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[Boris Zbarsky]

On 5/24/16 7:16 AM, Florin Mezei wrote:
> Is there any chance for this to break web compatibility?

Yes, there is, but seems pretty low. The Chrome intent to implement at
https://groups.google.com/a/chromium.org/d/msg/blink-dev/QWyCpJjgfY8/TOxG9n-OAQAJ
has some data. Quoting:

--------------------------------------
`form' content attribute of LABEL element is used in less than 0.0023%
of page views.
https://www.chromestatus.com/metrics/feature/timeline/popularity/986

label.form is different from label.control.form in less than 0.0016% of
page views.
https://www.chromestatus.com/metrics/feature/timeline/popularity/1261
---------------------------------------

-Boris