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(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==="INR"){
                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 amtval=amount.value;
        if(amtval===""||amtval<1){
            amtval=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 = amtval * rate;
        msg.innerText = `${amtval} ${fromcurr.value} = ${finalAmount} ${tocurr.value}`;
     });