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Re: Adopting a Custom Element into Another Document

From: Ryosuke Niwa <rniwa@apple.com>
Date: Tue, 13 Jan 2015 11:36:32 -0800
Cc: Webapps WG <public-webapps@w3.org>, Boris Zbarsky <bzbarsky@mit.edu>
Message-id: <A7AAAF1E-A764-47A3-AA35-253337255115@apple.com>
To: Anne van Kesteren <annevk@annevk.nl>
On Jan 13, 2015, at 11:27 AM, Anne van Kesteren <annevk@annevk.nl> wrote:

> On Tue, Jan 13, 2015 at 8:15 PM, Ryosuke Niwa <rniwa@apple.com> wrote:
>> By "the same thing", do you mean that they will manually change __proto__
>> themselves?
> 
> Yes.
> 
> 
>> Let's say we have MyElement that inherits from HTMLElement and we're
>> adopting an instance of this element (let's call it myElement) from a
>> document A to document B; MyElement is currently defined in A's global
>> object.
>> 
>> I have two questions:
>> 
>> Why did we decide to let custom elements handle this themselves instead of
>> doing it in the browser?
> 
> With two realms it's not a given that both realms use the same custom
> element registry. (As you acknowledge.)

Okay.

>> When "myElement" is adopted into B, there is no guarantee that MyElement is
>> also defined in B.  Does that mean MyElement may need to create another
>> class, let us call this MyElementB, in the B's context that inherits from
>> B's HTMLElement?
> 
> Well, if you control both realms I would assume you would give the same name.

I'm not sure I understand what you mean by that.  The name of the new class MyElementB isn't important.

Do you agree that the author has to create a new class in B if there is no definition of MyElement there?
But how do we even determine whether MyElement's defined in B?
And if did, how do we get the class's prototype?

>> Didn't Boris say Gecko needs to do this synchronously in order to enforce
>> their security policy?
> 
> I don't think that's conclusive, though if it turns out that's the
> case we would need different timing between normal and custom
> elements, yes.

Great. Thanks for the clarification.

- R. Niwa
Received on Tuesday, 13 January 2015 19:37:08 UTC

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