woocommerce_order_number │ filter-hook │ WC 1.0

Gets the order number for display (by default, order ID).

Usage

add_filter( 'woocommerce_order_number', 'wp_kama_woocommerce_order_number_filter', 10, 2 );

/**
 * Function for `woocommerce_order_number` filter-hook.
 * 
 * @param  $id   
 * @param  $that 
 *
 * @return 
 */
function wp_kama_woocommerce_order_number_filter( $id, $that ){

	// filter...
	return $id;
}

$id

-

$that

-

Where the hook is called

return (string) apply_filters( 'woocommerce_order_number', $this->get_id(), $this );

Where the hook is used in WooCommerce