以“现金”方式购买“无效付款方式”应导致“无效付款方式！”

Question

if (!["debit", "credit"].includes(paymentMethod)) {
      return "Invalid payment method!";
    } else if (paymentMethod === "debit") {
      valueTotal -= valueTotal * DISCOUNT;
    } else if (paymentMethod === "credit") {
      valueTotal += valueTotal * TAX;
    }

我需要验证此要求：以“现金”方式“使用无效的付款方式”购买应导致“无效的付款方式！”我做错了什么？

似乎没什么作用

Answer 1

您能否澄清一下这一说法：

我需要验证此要求：以“现金”方式“使用无效的付款方式”购买应导致“无效的付款方式！”我做错了什么？

我假设您有一个函数执行如下所示的操作。输出似乎按预期工作。只有“借方”和“贷方”输入不会返回“无效的付款方式”

const DISCOUNT = 0.1;
const TAX = 0.2;
let valueTotal = 100;

function processPayment( PaymentMethod){
    if (!["debit", "credit"].includes(PaymentMethod)) {
      return "Invalid payment method!";
    } else if (PaymentMethod === "debit") {
      valueTotal -= valueTotal * DISCOUNT;
    } else if (PaymentMethod === "credit") {
      valueTotal += valueTotal * TAX;
    }

    return "Good payment"
}

console.log(processPayment( "cash")) 
// Input:"cash" Output: "Invalid payment method!"

console.log(processPayment( "cheeseburger")) 
// Input:"cash" Output: "Invalid payment method!"

console.log(processPayment( "debit")) 
// Input:"debit" Output:  "Good payment"

console.log(processPayment( "credit")) 
// Input:"credit" Output:  "Good payment"