Writing a custom add-cart.php implementation allows developers to optimize performance to the absolute limits. By combining strict type checking on the num variable, real-time database stock validations, and cleanly structured JSON responses, you can easily deploy a high-quality checkout ecosystem capable of scaling to thousands of concurrent buyers. If you want to take this further, tell me:
Automated testing (PHPUnit) for cart logic is a sign of professional quality, but at minimum manual testing of these cases is mandatory. addcartphp num high quality