wp-includes/l10n.php:1443Determines whether there are translations for the text domain.
$domainstringboolfunction is_textdomain_loaded( $domain ) { global $l10n; return isset( $l10n[ $domain ] ) && ! $l10n[ $domain ] instanceof NOOP_Translations;}Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/l10n.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.