main.js

const currencyEl_one = document.getElementById('currency-one');
const currencyEl_two = document.getElementById('currency-two');
const amountEl_one = document.getElementById('amount-one');
const amountEl_two = document.getElementById('amount-two');

const rateEl = document.getElementById('rate');
const swap = document.getElementById('swap');

// Fetch exchange rates and updates the DOM
function calculate(){
  const currency_one = currencyEl_one.value;
  const currency_two = currencyEl_two.value;

  fetch(`https://api.exchangerate-api.com/v4/latest/${currency_one}`).then(res => res.json()).then(data =>{
    const rate = data.rates[currency_two];
    console.log('rate', rate)
    rateEl.innerHTML = `1 ${currency_one} = ${rate} ${currency_two}`;

    amountEl_two.value = (amountEl_one.value * rate).toFixed(2);
  });

}

// Event listeners
currencyEl_one.addEventListener('change', calculate);
amountEl_one.addEventListener('input', calculate);
currencyEl_two.addEventListener('change', calculate);
amountEl_two.addEventListener('input', calculate);

// Swap button
swap.addEventListener('click', () => {
  const temp = currencyEl_one.value;
  currencyEl_one.value = currencyEl_two.value;
  currencyEl_two.value = temp;
  calculate();
})

calculate();