Very little or none. But it’s easy to get carried away in the client with things like card number validation, detecting the card type based on number, date drop

Very little or none. But it’s easy to get carried away in the client with things like card number validation, detecting the card type based on number, date drop down picker for the expiry date, animation library for showing when it’s processing, etc. Let alone leaving in the standard includes like Google Analytics, tracking URLs, A/B testing tools, etc.