jQuery library that transforms credit card numbers via aesthetic formatting based on "defined" credit cards.
User inputs credit card number: 371449635398431 (American Express)
Result: 3714 4963539 8431
User inputs credit card number: 4111111111111111 (Visa)
Result: 4111 1111 1111 1111
User inputs credit card number: 2901000000000000 (Unknown)
Result: 2901000000000000
See a demo of the here.