Intl.NumberFormat

JavaScript course · Expert · Lesson 53/63

Learn locale-aware number and currency formatting with Intl.NumberFormat.

Intl.NumberFormat

Intl.NumberFormat formats numbers by locale. Each locale uses its own thousands separator and decimal mark: 1,234.56 in the US; 1.234,56 in Germany. You pass a locale string to the constructor: 'tr-TR', 'en-US', 'de-DE'. The format method takes a number and returns the formatted string. The options object controls style, fraction digits and currency. When you need a new formatter, call the constructor again.

Currency formatting

To format currency, set style: 'currency' and pass the ISO 4217 code in currency: 'TRY', 'EUR', 'USD'. Choose what appears in the output with currencyDisplay: 'symbol', 'narrowSymbol', 'code', 'name'. Decimal digits are controlled by minimumFractionDigits and maximumFractionDigits. Two digits are standard for most currencies; exceptions like the Japanese yen use zero.

Exercise EUR currency formatter

Create an Intl.NumberFormat for the 'de-DE' locale. Set style to 'currency' and currency to 'EUR'. Call format with 49.99 and assign the result to the price variable.

Show example solution

1. Create with new Intl.NumberFormat('de-DE', { ... }).
2. In options set style 'currency' and currency 'EUR'.
3. Call .format(49.99) and assign to price.

Example solution:
const price = new Intl.NumberFormat('de-DE', {
  style: 'currency',
  currency: 'EUR'
}).format(49.99);

Test yourself

What does the style field in the Intl.NumberFormat options decide?
- The formatting type: decimal, currency, percent or unit
- How many digits the number has
- Which locale is used
- Whether the output is uppercase
Show answer

The formatting type: decimal, currency, percent or unit — Correct. The style field picks the formatting type; currency also requires a currency code.

Add the EUR code

const price = new Intl.NumberFormat('tr-TR', { style: 'currency', currency: ____ }).format(1250);

Show answer

const price = new Intl.NumberFormat('tr-TR', { style: 'currency', currency: 'EUR' }).format(1250);

Match options to their meaning

style

Formatting type
currency

ISO 4217 code
minimumFractionDigits

Minimum fraction digits
currencyDisplay

Symbol or code

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Intl.NumberFormat