Bug: `hidden` attribute does not accept string values

[jantimon]

React version:

 "react": "18.3.0-next-522f47345-20220614",
 "react-dom": "18.3.0-next-522f47345-20220614",

Steps To Reproduce

<span hidden="until-found">Hello React<span>

Link to code example:

https://codesandbox.io/s/headless-violet-ygn593

The current behavior

React will turn hidden into a boolean attribute and removes "until-found":

The expected behavior

React does not strip "until-found" to allow using hidden-until-found in Chrome 102+ for better SEO and accessibility.

[hiddenest]

@eps1lon Hi! Is there an update on this issue?
Would be nice to have support for.

[pbsmultimedia]

+1

[mkrause]

Firefox 139 now also supports hidden="until-found".

[PeterDekkers]

This is also part of the targets for Interop 2025, so should see wide browser support later this year.

[nickshanks]

Also the empty string prop value should map to true (which then becomes an empty string attribute value again in the HTML).

[mkrause]

This is now supported in all major browsers (as of Safari 26.2 which came out today).