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I am trying to create a money exchange calculator . But the result is showing NaN.

What I have tried:

Here's the code
<pre lang="HTML">
<pre><head>
    <meta charset="utf-8">
    <title></title>
    <link rel="stylesheet" href="style.css">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <!-- FontAweome CDN Link for Icons -->
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css"/>
  </head>
  <body>
    <div class="wrapper">
      <header>Convert Currency</header>
      <form action="#">
        <div class="amount">
          <p>Enter Amount</p>
          <input type="text" value="1">
        </div>
        <div class="drop-list">
          <div class="from">
            <p>From</p>
            <div class="select-box">
              <img src="https://flagcdn.com/48x36/us.png" alt="flag">
              <select> <!-- Options tag are inserted from JavaScript --> </select>
            </div>
          </div>
          <div class="icon"></div>
          <div class="to">
            <p>To</p>
            <div class="select-box">
              <img src="https://flagcdn.com/48x36/np.png" alt="flag">
              <select> <!-- Options tag are inserted from JavaScript --> </select>
            </div>
          </div>
        </div>
        <div class="exchange-rate">Getting exchange rate...</div>
        <button>Show Result</button>
      </form>
    </div>
    <script src="js/country-list.js"></script>
    <script src="js/script.js"></script>
  </body>



JavaScript
   let country_list = {
    "AED" : "AE",
    "AFN" : "AF",
    "XCD" : "AG",
    "ALL" : "AL",
    "AMD" : "AM",
    "ANG" : "AN",
    "AOA" : "AO",
    "AQD" : "AQ",
    "ARS" : "AR",
    "AUD" : "AU",
    "AZN" : "AZ",
    "BAM" : "BA",
    "BBD" : "BB",
    "BDT" : "BD",
    "XOF" : "BE",
    "BGN" : "BG",
    "BHD" : "BH",
    "BIF" : "BI",
    "BMD" : "BM",
    "BND" : "BN",
    "BOB" : "BO",
    "BRL" : "BR",
    "BSD" : "BS",
    "NOK" : "BV",
    "BWP" : "BW",
    "BYR" : "BY",
    "BZD" : "BZ",
    "CAD" : "CA",
    "CDF" : "CD",
    "XAF" : "CF",
    "CHF" : "CH",
    "CLP" : "CL",
    "CNY" : "CN",
    "COP" : "CO",
    "CRC" : "CR",
    "CUP" : "CU",
    "CVE" : "CV",
    "CYP" : "CY",
    "CZK" : "CZ",
    "DJF" : "DJ",
    "DKK" : "DK",
    "DOP" : "DO",
    "DZD" : "DZ",
    "ECS" : "EC",
    "EEK" : "EE",
    "EGP" : "EG",
    "ETB" : "ET",
    "EUR" : "FR",
    "FJD" : "FJ",
    "FKP" : "FK",
    "GBP" : "GB",
    "GEL" : "GE",
    "GGP" : "GG",
    "GHS" : "GH",
    "GIP" : "GI",
    "GMD" : "GM",
    "GNF" : "GN",
    "GTQ" : "GT",
    "GYD" : "GY",
    "HKD" : "HK",
    "HNL" : "HN",
    "HRK" : "HR",
    "HTG" : "HT",
    "HUF" : "HU",
    "IDR" : "ID",
    "ILS" : "IL",
    "INR" : "IN",
    "IQD" : "IQ",
    "IRR" : "IR",
    "ISK" : "IS",
    "JMD" : "JM",
    "JOD" : "JO",
    "JPY" : "JP",
    "KES" : "KE",
    "KGS" : "KG",
    "KHR" : "KH",
    "KMF" : "KM",
    "KPW" : "KP",
    "KRW" : "KR",
    "KWD" : "KW",
    "KYD" : "KY",
    "KZT" : "KZ",
    "LAK" : "LA",
    "LBP" : "LB",
    "LKR" : "LK",
    "LRD" : "LR",
    "LSL" : "LS",
    "LTL" : "LT",
    "LVL" : "LV",
    "LYD" : "LY",
    "MAD" : "MA",
    "MDL" : "MD",
    "MGA" : "MG",
    "MKD" : "MK",
    "MMK" : "MM",
    "MNT" : "MN",
    "MOP" : "MO",
    "MRO" : "MR",
    "MTL" : "MT",
    "MUR" : "MU",
    "MVR" : "MV",
    "MWK" : "MW",
    "MXN" : "MX",
    "MYR" : "MY",
    "MZN" : "MZ",
    "NAD" : "NA",
    "XPF" : "NC",
    "NGN" : "NG",
    "NIO" : "NI",
    "NPR" : "NP",
    "NZD" : "NZ",
    "OMR" : "OM",
    "PAB" : "PA",
    "PEN" : "PE",
    "PGK" : "PG",
    "PHP" : "PH",
    "PKR" : "PK",
    "PLN" : "PL",
    "PYG" : "PY",
    "QAR" : "QA",
    "RON" : "RO",
    "RSD" : "RS",
    "RUB" : "RU",
    "RWF" : "RW",
    "SAR" : "SA",
    "SBD" : "SB",
    "SCR" : "SC",
    "SDG" : "SD",
    "SEK" : "SE",
    "SGD" : "SG",
    "SKK" : "SK",
    "SLL" : "SL",
    "SOS" : "SO",
    "SRD" : "SR",
    "STD" : "ST",
    "SVC" : "SV",
    "SYP" : "SY",
    "SZL" : "SZ",
    "THB" : "TH",
    "TJS" : "TJ",
    "TMT" : "TM",
    "TND" : "TN",
    "TOP" : "TO",
    "TRY" : "TR",
    "TTD" : "TT",
    "TWD" : "TW",
    "TZS" : "TZ",
    "UAH" : "UA",
    "UGX" : "UG",
    "USD" : "US",
    "UYU" : "UY",
    "UZS" : "UZ",
    "VEF" : "VE",
    "VND" : "VN",
    "VUV" : "VU",
    "YER" : "YE",
    "ZAR" : "ZA",
    "ZMK" : "ZM",
    "ZWD" : "ZW"
}
const dropList = document.querySelectorAll("form select"),
fromCurrency = document.querySelector(".from select"),
toCurrency = document.querySelector(".to select"),
getButton = document.querySelector("form button");

for (let i = 0; i < dropList.length; i++) {
    for(let currency_code in country_list){
        let selected = i == 0 ? currency_code == "USD" ? "selected" : "" : currency_code == "NPR" ? "selected" : "";
        let optionTag = `<option value="${currency_code}" ${selected}>${currency_code}</option>`;
        dropList[i].insertAdjacentHTML("beforeend", optionTag);
    }
    dropList[i].addEventListener("change", e =>{
        loadFlag(e.target);
    });
}

function loadFlag(element){
    for(let code in country_list){
        if(code == element.value){
            let imgTag = element.parentElement.querySelector("img");
            imgTag.src = `https://flagcdn.com/48x36/${country_list[code].toLowerCase()}.png`;
        }
    }
}

window.addEventListener("load", ()=>{
    getExchangeRate();
});

getButton.addEventListener("click", e =>{
    e.preventDefault();
    getExchangeRate();
});

const exchangeIcon = document.querySelector("form .icon");
exchangeIcon.addEventListener("click", ()=>{
    let tempCode = fromCurrency.value;
    fromCurrency.value = toCurrency.value;
    toCurrency.value = tempCode;
    loadFlag(fromCurrency);
    loadFlag(toCurrency);
    getExchangeRate();
})

function getExchangeRate(){
    const amount = document.querySelector("form input");
    const exchangeRateTxt = document.querySelector("form .exchange-rate");
    let amountVal = amount.value;
  amountVal = parseFloat(amountVal);
    if(amountVal == "" || amountVal == "0"){
        amount.value = "1";
        amountVal = 1;
    }
    exchangeRateTxt.innerText = "Getting exchange rate...";
    let url = `https://api.fastforex.io/convert?from=${fromCurrency.value}&to=${toCurrency.value}&amount=${amountVal}&api_key=xxxx-xxxxx-xxxxx`; //api key on purpose
fetch(url).then(response => response.json()).then(result =>{
    let exchangeRate = result.rate;
    let totalExRate = (amountVal * exchangeRate).toFixed(2);
    exchangeRateTxt.innerText = `${amountVal} ${fromCurrency.value} = ${totalExRate} ${toCurrency.value}`;
}).catch(() =>{
    exchangeRateTxt.innerText = "Something went wrong";
});
  
}


Response data:

{
"base": "AED",
"amount": 1,
"result": {
"USD": 0.27,
"rate": 0.27234
},
"ms": 5
}
Posted
Updated 9-Jan-23 3:08am

Nobody can run your code so it's impossible to tell what's causing the problem.

You also do no say where this "NaN" is showing up. Is it in the output on the page? Is it throwing an error?

"Nan" is the result of some math operation that generates a nonsensical result, like dividing by 0. If this value is in the output of the code, you're going to have to trace backwards in your code from the point where the output is returned to what code generated that output.

If the Nan is coming in the data of the API call you're making, you're going to have to debug the service if you wrote that. If not, you're going to have to contact the vendor for the service for help with the problem.
 
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You say your response data looks like:
JSON
{
    "base": "AED",
    "amount": 1,
    "result": {
        "USD": 0.27,
        "rate": 0.27234
    },
    "ms": 5
}
If that is correct, then there is no rate property on the response; you would need to read the result.rate property.

Since you've named the variable containing the parsed response as result, that means you would need result.result.rate.

You'll also want to test whether the parseFloat call worked, using the isNaN function.
JavaScript
async function getExchangeRate(){
    const amount = document.querySelector("form input");
    const exchangeRateTxt = document.querySelector("form .exchange-rate");
    let amountVal = amount.value;
    amountVal = parseFloat(amountVal);
    if (isNaN(amountVal) || amountVal == "0"){
        amount.value = "1";
        amountVal = 1;
    }
    
    exchangeRateTxt.innerText = "Getting exchange rate...";
    try {
        const url = `https://api.fastforex.io/convert?from=${fromCurrency.value}&to=${toCurrency.value}&amount=${amountVal}&api_key=xxxx-xxxxx-xxxxx`;
        const response = await fetch(url);
        const result = await response.json();
        const exchangeRate = result.result.rate;
        const totalExRate = (amountVal * exchangeRate).toFixed(2);
        exchangeRateTxt.innerText = `${amountVal} ${fromCurrency.value} = ${totalExRate} ${toCurrency.value}`;
    } catch {
        exchangeRateTxt.innerText = "Something went wrong";
    }
}
 
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