SDK Example: Add to Cart with Configuration Changes (Fall '19)

Use the example SDK code in this topic to add an already configured item to a cart.

```javascript
    const addToCartInput = digitalCommerce.createAddToCartInput();
    addToCartInput.catalogCode = "Phones";
    addToCartInput.offerConfiguration = digitalCommerce.getSelectedOffer(offerCode);
    addToCartInput.customFields = ["customAttribute__c"]; // optional field which returns custom fields for given keys
    input.basketAction = "AddAfterConfig";
    return digitalCommerce.addToCart(addToCartInput);
  })
  .then(addToCartResponse => {
    Logger.info(addToCartResponse.orderId);
  })
  .catch(error => {
    Logger.info("addToCart login user dual fail: " + error);
  });