let currency = prompt('Укажите валюту:');
let exchangeRateSymbol = '';

if(currency) {
	currency = currency.toLowerCase();
	if(currency === 'usd') {
		exchangeRateSymbol = '$';
	} else if(currency === 'eur') {
		exchangeRateSymbol = '€';
	} else {
		alert('Неверно указанная валюта');
	}
} else {
	alert('Укажите валюту:');
}

if(currency === 'usd' || currency === 'eur' ) {

	let quantity = +prompt('Укажите величину в гривне для обмена');

	const fetchExchangeRate = (currency) => {
		fetch(`https://open.er-api.com/v6/latest/${currency}`)
			.then(res => res.json())
			.then(data => {
				alert(`${quantity} грн в ${currency} = ${(quantity / data.rates.UAH).toFixed(2)}${exchangeRateSymbol}`);
			});
	}

	fetchExchangeRate(currency);
}