importNode and adoptNode should throw with passed a ShadowRoot

[inscriber]

Given that cloneNode throws with a shadow root, importNode should also throw because one of the steps in the import algorithm it to clone the node. Also, adoptNode should also throw because the host and shadow root shouldn't have different node documents.

[samgiles]

Does this necessitate a change in the DOM L4 spec? https://dom.spec.whatwg.org/#dom-document-importnodenode-deep to something along these lines (also adding the caveat for adoptNode):

The importNode(node, deep) method must run these steps:

• If node is a document or ShadowRoot, throw a NotSupportedError exception.
• Return a clone of node, with context object and the clone children flag set if deep is true.

[domenic]

In general basically all of the shadow DOM spec is a giant patch on the DOM spec, so that wouldn't be surprising. I would expect eventual integration once we get something shipping in multiple browsers...

[hayatoito]

Yeah, upstreaming Shadow DOM spec to DOM spec has been a long term goal for years.

For a small change like this, I think it's okay to update DOM spec directly rather than Shadow DOM spec.

[hayatoito]

BTW, we can use LayoutRoot here, rather than document or ShadowRoot.
See https://www.w3.org/Bugs/Public/show_bug.cgi?id=28748
Though LayoutRoot is still in the air. No one has started to work on this, I guess.

[annevk]

@samgiles would you be willing to submit a PR to https://github.com/whatwg/dom?

[hayatoito]

Thanks. Let me close this issue.