Session
    
    onChange
onChange Callback
The onChange( ) callback invokes the function registered against this event when the input value in the hosted field in the iFrame has changed.
Usage
PaymentSession.onChange([HostedFieldsRole], function(selector, role), [scope]);
Example
PaymentSession.onChange(['card.number', 'card.securityCode'], function(selector, role) {
    //handle change event
});
Arguments
        HostedFieldsRole
        
        Array
        REQUIRED
    
    An array of field roles for the hosted fields where the event occurred. Valid array of field roles:
card.nameOnCard
            card.number
            card.expiryMonth
            card.expiryYear
            card.securityCode
            giftCard.number
            giftCard.pin
            ach.bankAccountNumber
            ach.bankAccountNumberConfirmation
            ach.bankAccountHolder
            ach.routingNumber
            directDebitCanada.bankAccountNumberConfirmation
            directDebitCanada.bankAccountHolder
            directDebitCanada.bankAccountNumber
            directDebitCanada.financialInstitutionNumber
            directDebitCanada.transitNumber
            
        
        callbackFunction
        
        Function
        
    The callback function invoked with the selector and the role for the field whose proxy triggered the event.
        selector
        
        String
        
    Identifier of the HTML element that has changed or modified (ex: "#card-number").
        role
        
        String
        
    Valid array of field roles:
number
                nameOnCard
                expiryMonth
                expiryYear
                securityCode
                pin
                bankAccountNumber
                bankAccountNumberConfirmation
                bankAccountHolder
                routingNumber
                financialInstitutionNumber
                transitNumber
                
        scope
        
        String
        
    The optional named instance of a card payment data set within a session. See Multiple Hosted Sessions for more information.
Return Value
None