Formatting currency with JavaScript Intl

Javascript's Internationalization API allows you to format currency. It takes the locale and options to configure the currency we're using. The options require the style to be set to currency and a currency option to specify the unit type, as this is returned as part of the result.

Intl.NumberFormat("LOCALE", { style: "currency", currency: "CURRENCY UNIT"}).format(VALUE); // => "€1.23"

The following example formats a EUR (Euro) currency of the value 1.2345 into a en-GB (English - Great Britain) format.

Intl.NumberFormat("en-GB", { style: "currency", currency: "EUR"}).format(1.2345); // => "€1.23"

To save configureing this each time we use the formatting it can be wrapped in a function and the values passes to it. This example tahe the value and optionally a locale, defaulting to en-GB. It returns a USD value formatted to the input locale.

const formatUSDCurrency = (value, locale = "en-GB") => {
    return Intl.NumberFormat(locale, {
        style: "currency",
       currency: 'USD',
    }).format(value);
};


formatUSDCurrency(1230000) // => "US$1,230,000.00"
formatUSDCurrency(1230000, "de-DE") // => "1.230.000,00 $"
formatUSDCurrency(1230000, "fr-FR") // => "1 230 000,00 $US"

You can also configure significant digits, plus/minus signs and other settings as needed.

You can either specify the locale yourself, as I have done above, or you can get the user locale from the browser.