script.js

const BASE_URL = 
"https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@latest/v1/currencies";

const dropdowns = document.querySelectorAll(".dropdown select");
const btn = document.querySelector("form button");
const fromCurr = document.querySelector(".from select");
const toCurr = document.querySelector(".to select");
const msg = document.querySelector(".msg");

for(let select of dropdowns){
    for(let currCode in countryList){
        let newOption = document.createElement("option");
        newOption.innerText = currCode;
        newOption.value = currCode;
        if(select.name === "from" && currCode === "USD"){
            newOption.selected = "selected";
        }
        else if(select.name === "to" && currCode === "PKR"){
            newOption.selected = "selected";
        }
            
            select.append(newOption); 
    }

    select.addEventListener("change", (evt)=>{
        updateFlag(evt.target);
    })
}

const updateFlag = (element) =>{
    let currCode = element.value;
    let countryCode = countryList[currCode];
    let newSrc = `https://flagsapi.com/${countryCode}/flat/64.png`;
    let img = element.parentElement.querySelector("img");
    img.src = newSrc;
}


btn.addEventListener("click", async(evt) =>{
    evt.preventDefault();
    let amount = document.querySelector(".amount input");
    let amtvalue = amount.value;

    if(amtvalue === "" || amtvalue < 1){
        amtvalue = 1;
        amount.value = "1";
    }

    const URL = `${BASE_URL}/${fromCurr.value.toLowerCase()}.json`
    let response = await fetch(URL);
    let data = await response.json();
    let rate = data[fromCurr.value.toLowerCase()][toCurr.value.toLowerCase()];
    let finalAmount = (amtvalue * rate).toFixed(3);
    msg.innerText = `${amtvalue} ${fromCurr.value} = ${finalAmount} ${toCurr.value}`


});