Doesn't appear to be.

https://github.com/whatwg/html/pull/9841

https://github.com/whatwg/html/issues/9625

Seems to have been in the works since 2023, out in the open, with support from all major browser engines.

>Is that a proprietary HTML extension?

No, of course not. Web standards are whatever google decides they are.

TFA links to the spec - https://html.spec.whatwg.org/multipage/form-elements.html#at...

It's in Firefox and Safari

Have you been following how HTML has evolved over the past 20 years? Your comment suggests not.

It’s not entirely a standards-driven process. It’s common for browser vendors to just build stuff. That’s been a mixed blessing but it has definitely been faster than some W3C consortium debating “ergonomics” for years.

Successful additions get backported into the spec, slowly.

Marquee still works, we just don't tell marketing.

https://caniuse.com/mdn-html_elements_marquee

Chrome is the new IE. Whatever google decides will become a standard (both defacto due to them controlling the market and just shipping new version just in time and de-jure due to them financing W3C consortium and other standard bodies)

Man, that brought back memories.