const countries = [{

        code: "en-US",

        currency: "USD",

        country: "United States"

    },

    {

        code: "en-NG",

        currency: "NGN",

        country: "Nigeria"

      }

]

​

function formatAsMoney(amount, buyerCountry) {

    let toCurrency = "";

    let isFound = false;

    countries.forEach(country => {

        if (country.code === buyerCountry) { //I am not sure if you `country.name`, change the key accordingly

            toCurrency = (amount).toLocaleString(country.code, { style: "currency", currency: country.currency });

            isFound = true;

        }

    });

    if (!isFound) {

        toCurrency = (amount).toLocaleString("en-US", { style: "currency", currency: "USD" }); //here `en-US` should be a string

    }

    return toCurrency;

}

​

​

console.log(formatAsMoney(2.15, "en-CA"))