[whatwg] Form-associated elements and the parser

Adam Klein adamk at chromium.org
Tue Aug 6 16:27:59 PDT 2013

On Tue, Aug 6, 2013 at 4:21 PM, Jonas Sicking <jonas at sicking.cc> wrote:
> As I recall it (it was ages since I dealt with this), the tricky case
> that you need to handle is this one:
> http://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2432
> In this case, web compatibility requires that the <input> is
> associated with the form. Specifically hidden <input> elements would
> often end up moved, but still had to show up in form.elements as well
> as get submitted along with the form.

That case definitely makes sense to me, and I think it's fine to keep
that behavior for compat. The only one I'm asking to change is the
case when the <input> and <form> end up in different trees.

> On Tue, Aug 6, 2013 at 2:01 PM, Adam Klein <adamk at chromium.org> wrote:
>> Hixie opened my eyes last week to parser-association behavior of the
>> sort found at http://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2428.
>> In that case, an <input> in a detached tree is associated with a
>> <form> in the main document. This causes badness in WebKit and Blink
>> because the association between the <form> and the <input> (e.g., as
>> exposed in the HTMLFormElement.elements collection) is only weakly
>> held to avoid reference loops (and thus memory leaks). And that
>> weakness occasionally results in crashes when one of these objects is
>> collected before the other.
>> While all modern HTML parser implementations I tested seemed to agree
>> on their treatment of the above example (they all return "1" as
>> elements.length), this feature doesn't strike me as terribly useful.
>> And for what it's worth, it doesn't seem to be present in legacy IE.
>> I'm interested what others would think about changing the parser to
>> only associate a <form> with an <input> if both are in the same "home
>> subtree" (http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#home-subtree).
>> Or is there some deep web-compat reason for this parsing oddity?
>> - Adam

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