Function Parameter Default Pattern

parameterDefaultES6.js

/**
 * Let's say you have 
 * function getPromoCodeErrors(accountId, cart, cartProductItems, cartItems)
 * 
 * If you don't have one or more of these parameters, then you need nulls in to fill out the parameters
 * getPromoCodeErrors(accountId, null, null, cartItems)
 * 
 * With the below this is valid
 * getPromoCodeErrors({accountId, cartItems})
 * 
 * This too
 * getPromoCodeErrors({accountId, cartProductItems, cartItems, cart})
 * 
 * This too
 * getPromoCodeErrors()
 * 
 * Line 24 sets an empty parameter to an object.
 */
export async function getPromoCodeErrors({
  accountId = '',
  cart = {},
  cartProductItems = [],
  cartItems = {},
} = {}) {
  const promoCodeInfo = await getPromoCodeByCode(accountId, cart.promoCodes[0]);
  const orderItems = getOrderItems(cart, cartProductItems);
  const { validProducts, validCategories } = checkPromoCodeValidityForCart(cart, cartItems, promoCodeInfo);
  const { promoCodeError } = await checkPromoCodeThresholds({
    cart,
    cartProductItems,
    orderItems,
    promoCode: promoCodeInfo,
    validProducts,
    validCategories
  });
  return promoCodeError
};