\Dom\DocumentFragment::getElementById() is not supported

Description

The following code:

<?php
$d = \Dom\HTMLDocument::createFromString('<p id="a">b</p><p id="a">c</p>');
$df = $d->createDocumentFragment();
$df->getElementById('a');

Resulted in this output:

  Error  Call to undefined method Dom\DocumentFragment::getElementById().

But I expected this output instead:

(no output)

This method is present in the DOM spec: https://developer.mozilla.org/en-US/docs/Web/API/DocumentFragment/getElementById and the similar method ::querySelector is implemented; I can't tell if querySelector actually uses the ID index though or does a linear scan through the fragment. (Aka, this method should not just be implemented, it is expected to have O(1) performance.)

PHP Version

PHP 8.4.13 (cli) (built: Oct  1 2025 20:34:15) (NTS)
Copyright (c) The PHP Group
Built by Debian
Zend Engine v4.4.13, Copyright (c) Zend Technologies
    with Zend OPcache v8.4.13, Copyright (c), by Zend Technologies

Operating System

Ubuntu 24.04.1

Commencez par examiner la pull request liée et l’implémentation existante de Dom\DocumentFragment::querySelector mentionnée dans l’issue. Consultez la spécification du DOM concernant la sémantique de getElementById(), notamment les ID en double et le comportement de recherche attendu ; le travail est terminé lorsque la méthode est disponible et renvoie l’élément du fragment correspondant comme spécifié.