Javascript 整数未保存在循环中/部分工作

我是javascript新手，目前正在编写一个在终端中运行的基本文件。它的大部分都在发挥作用。它允许用户添加/删除信用并检查其信用。最后一部分是允许他们购买一种产品，并将该金额从他们的整体信贷中扣除

我遇到的问题是，虽然它确实显示购买物品时金额已被删除。当返回菜单并检查剩余的信用后，它会回到原来的金额

我尝试使用下面的代码来保存信用卡（即使在检查可用信用卡后也会这样做）：

但由于数组使用用户输入的数字，因此它将从总积分中删除该数字，而不是从实际价格中删除该数字。因此，例如，如果用户选择选项4，它将从信用卡中删除4，而实际上糖果是3英镑

---

如果您能提供任何帮助，我将不胜感激，因为我花了很长时间没有找到解决方案。

问题是，在他们购买产品后，您从未更新信用卡 下面这一行所做的只是他们希望你做对的程度：）

解决方案非常简单，更新信用，然后显示信用，例如：

if (index == 3) {
    credit = credit - 4;
    console.log('Thank you, your Candy has now been dispensed. Your total credit is now £' + credit);
}

所以你的代码应该是

 var readlineSync = require('readline-sync');
 var credit = 0;
 var removeCredit = 0;

 menu = [];
 menu[0] = "Purchase a product";
 menu[1] = "View your credit";
 menu[2] = "Add credit";
 menu[3] = "Retrieve a refund";
 menu[4] = "Quit!";

 products = [];
 products[0] = "Drink: £1";
 products[1] = "Crisps: £1";
 products[2] = "Chocolate: £2";
 products[3] = "Candy: £3";

 do {
     index = readlineSync.keyInSelect(menu, 'Please choose your option');
     if (index == 1) {
         console.log("The total amount of credit you have is: £", credit);
     }

     if (index == 2) {
         credit += readlineSync.questionInt('How much credit would you to purchase? ');
         console.log("The total amount of credit you have is: £" + credit);
     }

     if (index == 3) {
         credit -= readlineSync.questionInt('How much credit would you like to remove? ');
         console.log("This credit has now been removed, your total available credit is: £" + credit);
     }
     if (index == 0) {
         index = readlineSync.keyInSelect(products, 'What product would you like?');
         if (index == 0) {
            credit = credit - 1;
            console.log('Thank you, your Drink has now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 1) {
            credit = credit - 1;
            console.log('Thank you, your Crisps have now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 2) {
            credit = credit - 2;
            console.log('Thank you, your Chocolate has now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 3) {
            credit = credit - 3;
            console.log('Thank you, your Candy has now been dispensed. Your total credit is now £' + credit);
         }
     }
 } while (index != 4)

---

我对您的代码进行了一些清理，并修复了您观察到的问题：

var readlineSync = require('readline-sync');
var credit = 0;
var index;

var menu = [
    'Purchase a product',
    'View your credit',
    'Add credit',
    'Retrieve a refund',
    'Quit!'
];

var products = [
    'Drink',
    'Crisps',
    'Chocolate',
    'Candy'
];

var prices = [1, 1, 2, 3];

var productList = products.map(function(product, i) {
    return product + ': £' + prices[i];
});

do {
    index = readlineSync.keyInSelect(menu, 'Please choose your option');

    if (index == 1) {
        console.log('The total amount of credit you have is: £%d', credit);
    }

    if (index == 2) {
        credit += readlineSync.questionInt('How much credit would you to purchase? ');
        console.log('The total amount of credit you have is: £%d', credit);
    }

    if (index == 3) {
        credit -= readlineSync.questionInt('How much credit would you like to remove? ');
        console.log('This credit has now been removed, your total available credit is: £%d', credit);
    }

    if (index == 0) {
        index = readlineSync.keyInSelect(productList, 'What product would you like?');

        if (index >= 0 && index < products.length) {
            credit -= prices[index];
            console.log('Thank you, your %s has now been dispensed. Your total credit is now £%d', products[index], credit);
        }

        continue;
    }

} while(index != 4);

此函数遍历

products

中的值，对于每个值

product

和每个索引

i

，它以

product:.price

的格式返回一个新字符串，并将其存储到数组

productList

的相应索引中

我将您的

console.log

语句更改为使用内联格式以使其更清晰

%s

表示在此处放置字符串，

%d

表示在此处放置整数。然后使用以下参数填充这些格式说明符

我在上一个

if

块中添加了一个

continue

语句，以便尽早返回循环。这是因为

索引

被您选择的产品覆盖，因此它不再反映原始菜单选择

---

如果您对我的反馈有任何疑问，请随时发表评论。

Ahh感谢您澄清我的错误所在！它现在工作正常。再次感谢！感谢您花时间清理代码，最重要的是解释这些更改所做的工作。这有助于澄清我的理解，所以我感谢你们！这只是一个友好的提醒，如果答案解决了您的问题，通常会将其标记为正确答案，因为这样做既有助于您的声誉，也有助于我们的声誉。

 var readlineSync = require('readline-sync');
 var credit = 0;
 var removeCredit = 0;

 menu = [];
 menu[0] = "Purchase a product";
 menu[1] = "View your credit";
 menu[2] = "Add credit";
 menu[3] = "Retrieve a refund";
 menu[4] = "Quit!";

 products = [];
 products[0] = "Drink: £1";
 products[1] = "Crisps: £1";
 products[2] = "Chocolate: £2";
 products[3] = "Candy: £3";

 do {
     index = readlineSync.keyInSelect(menu, 'Please choose your option');
     if (index == 1) {
         console.log("The total amount of credit you have is: £", credit);
     }

     if (index == 2) {
         credit += readlineSync.questionInt('How much credit would you to purchase? ');
         console.log("The total amount of credit you have is: £" + credit);
     }

     if (index == 3) {
         credit -= readlineSync.questionInt('How much credit would you like to remove? ');
         console.log("This credit has now been removed, your total available credit is: £" + credit);
     }
     if (index == 0) {
         index = readlineSync.keyInSelect(products, 'What product would you like?');
         if (index == 0) {
            credit = credit - 1;
            console.log('Thank you, your Drink has now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 1) {
            credit = credit - 1;
            console.log('Thank you, your Crisps have now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 2) {
            credit = credit - 2;
            console.log('Thank you, your Chocolate has now been dispensed. Your total credit is now £' + credit);
         }
         if (index == 3) {
            credit = credit - 3;
            console.log('Thank you, your Candy has now been dispensed. Your total credit is now £' + credit);
         }
     }
 } while (index != 4)

var readlineSync = require('readline-sync');
var credit = 0;
var index;

var menu = [
    'Purchase a product',
    'View your credit',
    'Add credit',
    'Retrieve a refund',
    'Quit!'
];

var products = [
    'Drink',
    'Crisps',
    'Chocolate',
    'Candy'
];

var prices = [1, 1, 2, 3];

var productList = products.map(function(product, i) {
    return product + ': £' + prices[i];
});

do {
    index = readlineSync.keyInSelect(menu, 'Please choose your option');

    if (index == 1) {
        console.log('The total amount of credit you have is: £%d', credit);
    }

    if (index == 2) {
        credit += readlineSync.questionInt('How much credit would you to purchase? ');
        console.log('The total amount of credit you have is: £%d', credit);
    }

    if (index == 3) {
        credit -= readlineSync.questionInt('How much credit would you like to remove? ');
        console.log('This credit has now been removed, your total available credit is: £%d', credit);
    }

    if (index == 0) {
        index = readlineSync.keyInSelect(productList, 'What product would you like?');

        if (index >= 0 && index < products.length) {
            credit -= prices[index];
            console.log('Thank you, your %s has now been dispensed. Your total credit is now £%d', products[index], credit);
        }

        continue;
    }

} while(index != 4);

var productList = products.map(function(product, i) {
    return product + ': £' + prices[i];
});