Question

我正在尝试完成此练习：

询问用户他们有多少钱。
接下来，询问他们有哪种货币
最后，问问他们想要将其转换为
将货币转换为请求的输出
使用其他货币的值
您的代码必须至少使用两个函数。
一个函数应该计算转换。
一个函数应该使用转换后的货币和货币名称打印警报消息。

提示 - 使用两个转换函数可能是有意义的。一种功能是从任何货币转换为美元，另一种功能从美元转换为任何其他货币。

这是我的代码：

当我在浏览器中运行代码时，没有任何反应。如果我正在计算转换权，那么我不是真的，当我运行时，没有任何打印输出。

更新：好吧，我解决了问题所以它现在正在运行，但我仍然没有得到转换部分的功能

'use strict';
let money = Number(prompt("How much money do you have?."));
let moneyCurrency = prompt("What currency are you using?.");
let currencysys = prompt("What currency do you want to convert it to? EUR, JPY, GBP, USD, or  BRL");


function convertCurrency(currency, currencySystem) {
  if (currencySystem === 'JPY' || currencySystem === 'jpy') {
    return convertJPYtoUSD(currency);
  } 
  else if (currencySystem  === 'Eur' || currencySystem  === 'eur') {
    return convertEurtoUSD(currency);
  }  
  else if (currencySystem  === 'GBP'|| currencySystem  === 'gbp') {
    return convertGBPtoUSD(currency);
  }
  else if ( currencySystem  === 'BRL'|| currencySystem  === 'brl') {
    return convertBRLtoUSD(currency);
  }
}

function convertJPYtoUSD(JPY) {
  return  (JPY * 0.91);
}

function printCurrencyMessage(convertedCurrency, currencysys,round) {
  if (round === undefined || isNaN(Number(round))) {
    round = 0;
  }
}

console.log("The converted currency is "+currencySystem + ".");

更新2：我有点麻烦，数学代码不对100GBP到JPY应该是19,103.08但我得到的东西完全不同

'use strict';
let money = Number(prompt("How much money do you have?."));
let moneyCurrency = prompt("What currency are you using?.");
let currencysys = prompt("What currency do you want to convert it to? EUR, JPY, GBP, USD, or  BRL");



`let currentExchange = {
"USD": 1,
"EURO" : 0.91,
"JPY" : 124.17,
"GBP" : 0.65,
"BRL" : 3.51,
}`

`let currentExchanges=currentExchange[currency];`

`function convertCurrency( currencyNeeded, moneyAmount) {
let exchange_value = moneyAmount * exchange_factor
return exchange_value


function convertCurrency( currencyNeeded, moneyAmount) {
let exchange_factor = currentExchange[currencyNeeded];
let exchange_value =  moneyAmount / exchange_factor
let value = moneyAmount * exchange_factor
console.log("The converted amount is $ " + (exchange_value.toFixed(2)) + "in " + currencyNeeded+ ".");

return exchange_value
};

convertCurrency(currencyNeeded,  moneyAmount);

Answer 1

<强> TDLR;

您正在尝试警告未定义的变量。

我建议你让你的功能为你回报你的价值。类似的东西：

console.log("The converted currency is "+ convertToCurrency(moneyCurrency, currencysys + ".");

更深入地解释和挖掘

您的签名

function convertCurrency(currency, currencySystem) {...

创建一个局部变量“currencySystem”，它不能在函数范围之外引用。因此，currencySystem是该函数的局部变量。

一些通用代码/架构建议：

使变量名更有意义和一致。

使用所有货币转换比率创建一个hashmap / object，并使用单个函数进行数学转换。 IE：

var currencies = {
    usd: {
        conversion: 1,
    },
    eur: {
        conversion: .89
    },
    ...
};

function convertCurrency(fromCurrency, toCurrency, amount) {

    // ... not the best at thinking of the algorithm. Suggestions?
    // perhaps normalize fromCurrency to the dollar, then convert to toCurrency since I believe the dollar is the base/universal currency
};

var convertedCurrency = convertCurrency("USD", "EUR", 20.50);

alert("The converted amount is" + convertedCurrency);

如果你需要多个功能作为一项要求，拆分成每个货币转换并不是一个可怕的想法，但似乎有点开销。

这是最终的解决方案：

'use strict';
let amount = Number(prompt("How much money do you have?."));
let currentCurrency = prompt("What currency are you using?");
let desiredCurrency = prompt("What currency do you want to convert it to? EUR, JPY, GBP, USD, or  BRL");

var currencyRates = {
    "USD": 1,
  "EUR": .8,
  "JPY": .7,
  "XXX": 5
};

function convertCurrency(currentCurrency, desiredCurrency, amount) {
  var currentRate = currencyRates[currentCurrency];
  var desiredRate = currencyRates[desiredCurrency];

  var USDAmount = amount * currentRate;
  var convertedAmount = USDAmount / desiredRate;

  return convertedAmount; // I think this is the right algorithm :/
}



var convertedCurrencyAmount = convertCurrency(currentCurrency, desiredCurrency, amount);

alert ("Converted: " + convertedCurrencyAmount);

Javascript中的货币转换器

1 个答案: