See more Promo Code template variations.
When the user begins to type their credit card into the form field, we apply classes to highlight the specific icon of the card they’re using. For example, 34 or 37 is American Express, 4 is Visa, and 51 through 55 is Mastercard. This is controlled by adding
data-credit-card-display to the text input element in conjunction with the politespace classes
The source code for this behavior is part of formcore.