Answer: As of the v2.6.1912.1301-beta, you can specify an event to trigger a callback-based on events in the iField using the function addIfieldCallback (event, callback). This callback will receive some data about events in the iField, such as whether the card number and/or CVV are valid. The card number validation is based on minimum and maximum lengths and whether it passes the Luhn check. The CVV validation is based on the length, depending on the card issuer.