Credit Card Matching

The following patterns are useful for first stage of credit card validation for Visa and Mastercards.

Visa pattern:

 /^4\d{3}-?\d{4}-?\d{4}-?\d{4}$/

Mastercard pattern:

 /^5[1-5]\d{2}-?\d{4}-?\d{4}-?\d{4}$/

This does not prove the number is valid but that it contains the correct content so it is a handy and light weight first stage validation.

To fully validate you must calculate a check digit. If this check digit is divisible by 10 then you have validated the Visa or Mastercard number!