address.js

function getBillingAddress({
  firstName,
  lastName,
  street,
  addressLineTwo,
  city,
  state,
  zip,
} ) {
  return {
    billingFirstName: firstName,
    billingLastName: lastName,
    billingAddressLineOne: street,
    billingAddressLineTwo: addressLineTwo,
    billingCity: city,
    billingState: state,
    billingZip: zip,
  };
}

function generateBillingAddress(order) {
  const {
    billingAddress,
    shippingAddress,
  } = order;
  const billingAddressData = billingAddress || shippingAddress;
  return getBillingAddress(billingAddressData);
}