demo · v141

Reveal Hidden

Hit your browser's Find-in-page (Ctrl/Cmd+F) and search for palantir or kestrel. Hidden collapsed sections open automatically, and any <details> ancestors expand to reveal the match. The event log proves the spec algorithm ran.

probing hidden=until-found + beforematch…

Field guide to obscure raptors

The following entries are collapsed by default. Search the page or expand them manually.

Owls

Most owls are nocturnal. Some, like the snowy owl, hunt during the day.

Eagles

Large birds of prey with broad wings. Two notable European species are the golden and the white-tailed.

Mythical
Falcons

Built for speed. Peregrines are the fastest animals on Earth in a dive.

the markup

<details>
  <summary>Mythical</summary>
  <div hidden="until-found">
    <p>The palantir isn't a real raptor.</p>
  </div>
</details>

document.getElementById("section").addEventListener("beforematch", () => {
  // Chrome 141 fires this just before find-in-page reveals the element.
  // Updated spec also expands closed <details> ancestors.
});

see also