How to easily format currency in Javascript without external libraries

currencyFormatter.js

class Payment {

    constructor(amount, currency) {
        this.amount = amount;
        this.currency = currency;
    }

    get localeMap() {
        return {
            USD: "en-US",
            EUR: "de-DE",
            JPY: "jp-JP",
            GBP: "en-GB"
        };
    }

    toString() {
        const locale = this.localeMap[this.currency];

        const intl = new Intl.NumberFormat(locale, {
            style: "currency",
            currency: this.currency
        });

        return intl.format(this.amount);
    }
}

const payments = [
    new Payment(0, "USD"),
    new Payment(10.50, "EUR"),
    new Payment(15.123, "JPY"),
    new Payment(600.314578, "GBP")
];

/**
 * This loop will print:
 * $0.00
 * € 10.50
 * JP¥ 15
 * £ 600.31
 **/
payments.forEach(payment => {
    console.log(payment.toString());
});