Add support for the popover API and for the name attribute on details elements.

[SylvainBoilard]

Hello,

This PR initially added support for the name attribute and specifying a toggle event handler for a details element, and was extended to implement the popover API.

See:

• https://html.spec.whatwg.org/multipage/popover.html ;
• https://html.spec.whatwg.org/multipage/indices.html#event-toggle ;
• https://html.spec.whatwg.org/multipage/interactive-elements.html#the-details-element ;
• https://developer.mozilla.org/en-US/docs/Web/API/Popover_API ;
• https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details#events ;
• https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details#attributes .

See also these related PRs:

• #1728 in js_of_ocaml
• #1734 in js_of_ocaml
• #806 in eliom

Please let me know of any issues.

Cheers,

[Drup]

Thanks !

If I'm reading the spec right, toggle is a valid event for any popover element ... which can be any HTML element. In that case, ontoggle should be a global attribute.

Is that right ? Can you do the modification accordingly ?

[SylvainBoilard]

Yes that is absolutely right; I had initially planned to limit the scope of this PR to the details element but following your input I decided to update it to support the popover API.

[balat]

Hello @Drup what do you think of the new version?

[Copilot]

Pull request overview

This PR adds comprehensive support for the modern HTML Popover API and extends the details element with the name attribute, enabling named exclusive accordions. The implementation follows HTML specification and is consistent with existing library patterns.

Key Changes:

• Implements the Popover API with popover, popovertarget, and popovertargetaction attributes
• Adds name attribute to details elements for exclusive accordion groups
• Introduces toggle and beforetoggle event handlers for popover and details state changes

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
lib/html_types.mli	Defines type signatures for new popover attributes (Popover, Popovertarget, Popovertargetaction), events (OnBeforeToggle, OnToggle), and extends details_attrib with Name; adds new variants (Manual, Hide, Show, Toggle) to big_variant
lib/html_sigs.mli	Declares function signatures for event handlers (a_onbeforetoggle, a_ontoggle) and attribute constructors (a_popover, a_popovertarget, a_popovertargetaction)
lib/html_f.ml	Implements event handlers and attribute constructors using existing library primitives; extends string_of_big_variant to convert new variant values to HTML-compliant strings
CHANGES.md	Documents the addition of popover API support and details name attribute

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