Число в строку валюты

const toCurrency = (n, curr, LanguageFormat = undefined) =>
  Intl.NumberFormat(LanguageFormat, {
    style: 'currency',
    currency: curr,
  }).format(n);

toCurrency(123456.789, 'EUR');
// €123,456.79  | currency: Euro | currencyLangFormat: Local
toCurrency(123456.789, 'USD', 'en-us');
// $123,456.79  | currency: US Dollar | currencyLangFormat: English (United States)
toCurrency(123456.789, 'USD', 'fa');
// ۱۲۳٬۴۵۶٫۷۹ ؜$ | currency: US Dollar | currencyLangFormat: Farsi
toCurrency(322342436423.2435, 'JPY');
// ¥322,342,436,423 | currency: Japanese Yen | currencyLangFormat: Local
toCurrency(322342436423.2435, 'JPY', 'fi');
// 322 342 436 423 ¥ | currency: Japanese Yen | currencyLangFormat: Finnish