Letting a customer enter a credit card and then parsing it on to the credit card processor means that you would need to be some level PCI complainant. You really really don't want to be close enough to the credit card numbers to do something with them, especially client side.

Having the credit card field, where you can access it, means that you become a target for people wanting to inject javascript into your site. Perhaps you're safe, but what about all the third party javascript libraries or tracking/remarketing/tracking script most sites have?

Sorry, it's a really bad idea. Let you credit card processor deal with the that hassle.