Re: [webcomponents] Custom elements disconnected from a document should not be upgraded (#419)

I would really prefer not to introduce this kind of inconsistency by requiring document-insertion for upgrade. Developers do complicated and interesting things with elements before inserting them into documents, as part of libraries and such. They shouldn't need to do some kind of insert-then-remove dance to get their elements to have the correct prototype and behavior.

I would prefer to keep the list of unresolved elements as the spec currently has them. It could be made a weak set in the spec, and implementers can either implement that immediately or will wait until they see problems in practice caused by lots of unused un-upgraded elements. I know Blink has implemented such things in the past with just weak references without a problem (we do that for the unhandled promises weak set).

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/issues/419#issuecomment-193289828