A proposal to help with testing/SEO/accessibility of closed ShadowDOM

[BronislavKlucka]

Hi as mentioned above, this is to help with those issues, not to solve them all, but how about adding

DocumentFragment Element.prototype.cloneShadowDOM()

I hope the signature is self-explanatory and the usecases are quite clear, since we've been discussing those issues for a quite some time.

This would allow closed ShadowDOM to remain closed, but allow crawling copy by script

Brona

[rniwa]

I'd prefer making cloneNode take a dictionary and make add this as an option instead if we can make the first argument polymorphic between boolean and a dictionary:
e.g. element.cloneNode({shadow: true}), element.cloneNode({deep: true, shadow:true}).

[annevk]

I don't understand "allow crawling copy by script". Are you suggesting that returns a deep copy of the shadow root that is now accessible and no longer a shadow root but a DocumentFragment node? Why would that be good?

@rniwa that makes more sense to me...

[hayatoito]

Yeah, I think the proposal does not solve an issue at all... :(
You will get yet another instance of "something which is closed". Both instances should stay closed.

[treshugart]

Is it possible to return a readonly tree from shadowRoot if it's closed instead of returning null?

[annevk]

@treshugart I don't know what that means. What is a readonly tree?

[treshugart]

Immutable representation of the current state of the shadow root.

[annevk]

1. That's not possible without inventing all sorts of new data structures.
2. That goes against what "closed" means.

[BronislavKlucka]

Appearently it was not as obvious as I assumed
The intent is not to clone shadowRoot, but the content of the shadowRoot

<x-user>
  #shadowRoot
     <h1>Brona</h2>
     <span>Czech Republic</span> 
</x-user>

var docFrag = document.querySelector("x-user").cloneShadowDOM()

docFrag:

#DocumentFragment
  <h1>Brona</h2>
  <span>Czech Republic</span> 

the copy is of the content of the shadowRoot, not the shadowRoot itself. No open, closed mode applies. It is regular DocumentFragment This allows for content to be crawled for testing/SEO/accessibility purposes while leaving the original closed shadowRoot intact

[annevk]

That is what I assumed you meant in #505 (comment). As far as I can tell that still leaks the kind of thing "closed" does not want to leak.

[BronislavKlucka]

I assumed, the reason for closed is "not to be tempered with", not necessary "not to be read"

[andyearnshaw]

Reading it means that your program could become dependant on the internal state of the tree, which defeats one of the advantages closed provides.

For automated testing, consideration for shadow trees really needs adding to the WebDriver spec. This has to be done regardless of any new methods that could be added to web components, so there's little point in adding them purely for that purpose.