JavaScript shop脚本无法正常运行

Question

我正在尝试使此商店脚本包含以下条件：

1. 余额不能低于0
2. 如果没有足够的资金，将使用代金券。
3. 它记录了凭证的使用和成功确认。

现在，余额确实降到了零以下，并且优惠券没有被使用……也许这很明显，但是我却发疯了。

另外，有什么技巧可以优化此代码？

谢谢！ 很抱歉，这很明显。 我是新手！

var total = 500;
var balance = 400;
var voucher = 100;
useVoucher = true;

if ( (total > balance) || (balance < 0) ) {
console.log("Insufficient funds. The total is " + total + "$ and you only have a balance of " + balance + "$.");
} else if (useVoucher = true) {
total = total - voucher
console.log(voucher + "$ Voucher applied. The new total is " + total + "$.");
} else {
console.log("You can't afford this item");
} 

if ((balance - total < 0) && balance > total); {
console.log("Success! You have a new balance of " + (balance - total) + "$.");
}

Answer 1

有几个错误，这是固定版本：

var total = 500;
var balance = 400;
var voucher = 100;
useVoucher = true;

if ( (total > balance) || (balance < 0) ) {
    console.log("Insufficient funds. The total is " + total + "$ and you only have a balance of " + balance + "$.");
} else if (useVoucher) {
    total = total - voucher
    console.log(voucher + "$ Voucher applied. The new total is " + total + "$.");
} else {
    console.log("You can't afford this item");
} 

if ((balance - total > 0) > 0 && balance > total) {
    console.log("Success! You have a new balance of " + (balance - total) + "$.");
}

1. 不要使用; 在您的if语句中。 这是不必要的，并且会导致您的逻辑执行不正确。
2. 不这样做(useVoucher = true)这会将true值分配给变量useVoucher而不是检查它是否为true 。 改为(useVoucher) 。 这将检查useVoucher是否具有不等于false 。

Answer 2

再次尝试检查您的逻辑。 优惠券似乎只有在有足够金额时才会使用。 我认为您应该删除“ else if”逻辑，并在第一个“ if”块中输入优惠券用法。

Answer 3

首先，您必须检查是否可以使用凭证。 如果您没有足够的余额，但是使用凭证有足够的余额，则会发生这种情况。

在这种情况下，请使用优惠券。

比检查您是否有足够的余额来支付或不支付。

这是代码：

var total = 500;
var balance = 400;
var voucher = 100;
useVoucher = true;


if (total > balance     // Not enough balance
      && useVoucher     // You can use the voucher
      && total - voucher <= balance) {  // Total minus voucher is under balance
  console.log(voucher + "$ Voucher applied. The new total is " + total + "$.");
  // IN this case use voucher
  total = total - voucher;

  // Would be better to check here if total is under 0, 
  // otherwise in the next few lines of code you will increase your balance.
} 

if (total <= balance) {   // Check if you have enough balance
  balance = balance - total;
  console.log("Success! You have a new balance of " + balance + "$.");
} else {                  // Not enough balance
  console.log("Insufficient funds. The total is " + total + "$ and you only have a balance of " + balance + "$.");
}

应该做额外的检查以检查凭证是否大于总数。通常使用凭证，如果凭证的价格大于价格，则您会浪费多余的钱，但是在这种情况下，我没有添加此支票，因为没有明确要求。

Answer 4

debugger;
var total = 500;
var balance = 400;
var voucher = 100;
var balanceWithVoucher = balance + voucher;
total > balance ? useVoucher = true : useVoucher = false;


if ((total > balance && total > balanceWithVoucher) || (balance < 0)) {
    console.log("Insufficient funds. The total is " + total + "$ and you only have a balance of " + balance + "$.");
} else if (useVoucher == true) {
    total = total - voucher
    console.log(voucher + "$ Voucher applied. The new total is " + total + "$.");
} else {
    console.log("You can't afford this item");
}
if ((balance - total > 0) && balance > total); {
    console.log("Success! You have a new balance of " + (balance - total) + "$.");
}