determine_locale(): string

123function determine_locale() {124	/**125	 * Filters the locale for the current request prior to the default determination process.126	 *127	 * Using this filter allows to override the default logic, effectively short-circuiting the function.128	 *129	 * @since 5.0.0130	 *131	 * @param string|null $locale The locale to return and short-circuit. Default null.132	 */133	$determined_locale = apply_filters( 'pre_determine_locale', null );134 135	if ( $determined_locale && is_string( $determined_locale ) ) {136		return $determined_locale;137	}138 139	if (140		isset( $GLOBALS['pagenow'] ) && 'wp-login.php' === $GLOBALS['pagenow'] &&141		( ! empty( $_GET['wp_lang'] ) || ! empty( $_COOKIE['wp_lang'] ) )142	) {143		if ( ! empty( $_GET['wp_lang'] ) ) {144			$determined_locale = sanitize_locale_name( $_GET['wp_lang'] );145		} else {146			$determined_locale = sanitize_locale_name( $_COOKIE['wp_lang'] );147		}148	} elseif (149		is_admin() ||150		( isset( $_GET['_locale'] ) && 'user' === $_GET['_locale'] && wp_is_json_request() )151	) {152		$determined_locale = get_user_locale();153	} elseif (154		( ! empty( $_REQUEST['language'] ) || isset( $GLOBALS['wp_local_package'] ) )155		&& wp_installing()156	) {157		if ( ! empty( $_REQUEST['language'] ) ) {158			$determined_locale = sanitize_locale_name( $_REQUEST['language'] );159		} else {160			$determined_locale = $GLOBALS['wp_local_package'];161		}162	}163 164	if ( ! $determined_locale ) {165		$determined_locale = get_locale();166	}167 168	/**169	 * Filters the locale for the current request.170	 *171	 * @since 5.0.0172	 *173	 * @param string $determined_locale The locale.174	 */175	return apply_filters( 'determine_locale', $determined_locale );176}