Recurly js Card Element event handling
User should be able to continue entering credit card, without needing to click to MM/YY, etc. Continuing to type should move to next relevant box through js. Because tried with external script is not working for reculry element.
This gets complicated when you consider that not all credit cards have the same number of digits in the card number. American Express, for example, is of the form: XXXX-XXXXXX-XXXXX (15 digits) whereas a Visa/MasterCard is of the form: XXXX-XXXX-XXXX-XXXX (16 digits)