Edit in JSFiddle

// Initialize
var worker = new encrypter({
    mode: 'NORENDER',
	  fields: {
        HolderName: {
            label: 'Nom du titulaire',
            elementSelector: '#fieldInputHolderName'
        },
        CardType: {
           label: 'Type de carte',
           values: [
               'visa',
               'mastercard',
               'jbl',
               'amex'
           ],
           defaultValue: 'amex'
        },
        CardNumber: {
            label: 'Numéro de carte'
        }
    },
    key: {
        contents: '-----BEGIN PUBLIC KEY-----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-----END PUBLIC KEY-----',
        identifier: 'public-key-0001'
    }
});

var paymentMethod = worker.getCurrentPaymentMethod();
var fields = paymentMethod.getFields();

var fieldHolderName = fields['HolderName'];
var fieldCardType = fields['CardType'];
var fieldCardNumber = fields['CardNumber'];

console.log(fieldHolderName.getElementSelector()); // #fieldInputHolderName
console.log(fieldCardType.getDefaultValue()); // amex
console.log(fieldCardNumber.getLabel()); // Numéro de carte