woocommerce_product_is_on_sale │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_product_is_on_sale', 'wp_kama_woocommerce_product_is_on_sale_filter', 10, 2 );

/**
 * Function for `woocommerce_product_is_on_sale` filter-hook.
 * 
 * @param  $on_sale 
 * @param  $that    
 *
 * @return 
 */
function wp_kama_woocommerce_product_is_on_sale_filter( $on_sale, $that ){

	// filter...
	return $on_sale;
}

$on_sale

-

$that

-

Where the hook is called

return 'view' === $context ? apply_filters( 'woocommerce_product_is_on_sale', $on_sale, $this ) : $on_sale;

return 'view' === $context ? apply_filters( 'woocommerce_product_is_on_sale', $on_sale, $this ) : $on_sale;

return 'view' === $context ? apply_filters( 'woocommerce_product_is_on_sale', $on_sale, $this ) : $on_sale;

Where the hook is used in WooCommerce