addEventListener on a Secure Fields instance or on fields,
passing one of the supported events and a callback. removeEventListener
removes a previously attached event handler.
Global events
The following events can be listened to by attaching an event handler to theSecureFields instance using the addEventListener method.
Field events
The following events can be listened to by attaching an event handler to a field (returned by theaddCardNumberField, addExpiryDateField,
addSecurityCodeField and addField methods) using the addEventListener method.
Some of these provide additional useful data like the card BIN, validation
status, and scheme. For example, the input event on a card number field might
include { schema: 'visa', codeLabel: 'CVV', valid: true, ... }.