If a Custom Element is used as a placeholder for an HTML heading, would it be interpreted as a heading for SEO purposes?

[TimeDropsSB]

I have a Custom Element, <our-h1>. <our-h1> is a placeholder such that when it is upgraded, it becomes a regular <h1> through DOM manipulation - that is, <our-h1> is replaced with <h1>.

In terms of SEO, would the constructed <h1> from <our-h1> be the same as if it was using an <h1> directly?

[domenic]

It depends on whether the search engine in question understands custom elements. That's not going to have a single easy answer, unfortunately.

[trusktr]

This is a problem that can be solved by Element Behaviors. See the section "augment existing HTML applications".

If you don't really need to extend from a heading element, you can just apply functionality as a behavior. (see working implementation)

[trusktr]

It depends on whether the search engine in question understands custom elements.

Probably that's a problem right now. F.e., @Sylphony, a bot that just reads HTML strings (without looking at the JavaScript DOM objects) could not possibly know that <my-header-1> is an extended <h1>.

[annevk]

This is already addressed by the standard: https://html.spec.whatwg.org/#custom-elements-autonomous-drawbacks.

[OvermindDL1]

And for note, this is one thing that the is="..." solves.