username_exists( string $username ): int|false

2078function username_exists( $username ) {2079	$user = get_user_by( 'login', $username );2080	if ( $user ) {2081		$user_id = $user->ID;2082	} else {2083		$user_id = false;2084	}2085 2086	/**2087	 * Filters whether the given username exists.2088	 *2089	 * @since 4.9.02090	 *2091	 * @param int|false $user_id  The user ID associated with the username,2092	 *                            or false if the username does not exist.2093	 * @param string    $username The username to check for existence.2094	 */2095	return apply_filters( 'username_exists', $user_id, $username );2096}