WP_REST_Request::offsetExists( string $offset )

Source

File: wp-includes/rest-api/class-wp-rest-request.php

public function offsetExists( $offset ) {
		$order = $this->get_parameter_order();

		foreach ( $order as $type ) {
			if ( isset( $this->params[ $type ][ $offset ] ) ) {
				return true;
			}
		}

		return false;
	}