wp-includes/user.php:2110Checks whether a username is valid.
$usernamestringboolOne hook fires while validate_username() runs, in this order:
Filters whether the provided username is valid.
function validate_username( $username ) { $sanitized = sanitize_user( $username, true ); $valid = ( $sanitized === $username && ! empty( $sanitized ) ); /** * Filters whether the provided username is valid. * * @since 2.0.1 * * @param bool $valid Whether given username is valid. * @param string $username Username to check. */ return apply_filters( 'validate_username', $valid, $username );}Introduced in 2.0.1. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/user.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.