Number.prototype.toLocaleString()

The toLocaleString() method returns a string with a language-sensitive representation of this number.

Try it

Syntax

toLocaleString()
toLocaleString(locales)
toLocaleString(locales, options)

Parameters

The locales and options parameters customize the behavior of the function and let applications specify the language whose formatting conventions should be used. In implementations, which ignore the locales and options arguments, the locale used and the form of the string returned are entirely implementation-dependent.

locales Optional

A string containing the locale to convert to.

options Optional

An object with some or all of the following properties:

currency

The currency to use in currency formatting. Possible values are the ISO 4217 currency codes, such as "USD" for the US dollar, "EUR" for the euro, or "CNY" for the Chinese RMB — see the Current currency & funds code list. There is no default value; if the style is "currency", the currency property must be provided.

currencyDisplay

How to display the currency in currency formatting. Possible values are:

  • "symbol" to use a localized currency symbol such as €, this is the default value,
  • "code" to use the ISO currency code,
  • "name" to use a localized currency name such as "dollar",
localeMatcher

The locale matching algorithm to use. Possible values are "lookup" and "best fit"; the default is "best fit". For information about this option, see the Intl page.

style

The formatting style to use , the default is "decimal".

  • "decimal" for plain number formatting.
  • "currency" for currency formatting.
  • "percent" for percent formatting
useGrouping

Whether to use grouping separators. The default is true.

  • "true": display grouping separators even if the locale prefers otherwise
  • "false": do not display grouping separators

The following properties fall into two groups: minimumIntegerDigits, minimumFractionDigits, and maximumFractionDigits in one group, minimumSignificantDigits and maximumSignificantDigits in the other. If at least one property from the second group is defined, then the first group is ignored.

minimumIntegerDigits

The minimum number of integer digits to use. Possible values are from 1 to 21; the default is 1.

minimumFractionDigits

The minimum number of fraction digits to use. Possible values are from 0 to 20; the default for plain number and percent formatting is 0; the default for currency formatting is the number of minor unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information).

maximumFractionDigits

The maximum number of fraction digits to use. Possible values are from 0 to 20; the default for plain number formatting is the larger of minimumFractionDigits and 3; the default for currency formatting is the larger of minimumFractionDigits and the number of minor unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information); the default for percent formatting is the larger of minimumFractionDigits and 0.

minimumSignificantDigits

The minimum number of significant digits to use. Possible values are from 1 to 21; the default is 1.

maximumSignificantDigits

The maximum number of significant digits to use. Possible values are from 1 to 21; the default is 21.

See the Intl.NumberFormat() constructor for details on these parameters and how to use them.

Return value

A string with a language-sensitive representation of the given number.

Performance

When formatting large numbers of numbers, it is better to create a Intl.NumberFormat object and use the function provided by its format property.

Examples

Using toLocaleString

In basic use without specifying a locale, a formatted string in the default locale and with default options is returned.

const number = 3500;

console.log(number.toLocaleString()); // Displays "3,500" if in U.S. English locale

Checking for support for locales and options arguments

The locales and options arguments are not supported in all browsers yet. To check for support in ES5.1 and later implementations, the requirement that illegal language tags are rejected with a RangeError exception can be used:

function toLocaleStringSupportsLocales() {
  const number = 0;
  try {
    number.toLocaleString('i');
  } catch (e) {
    return e.name === 'RangeError';
  }
  return false;
}

Prior to ES5.1, implementations were not required to throw a range error exception if toLocaleString is called with arguments.

A check that works in all hosts, including those supporting ECMA-262 prior to ed 5.1, is to test for the features specified in ECMA-402 that are required to support regional options for Number.prototype.toLocaleString directly:

function toLocaleStringSupportsOptions() {
  return !!(typeof Intl == 'object' && Intl && typeof Intl.NumberFormat == 'function');
}

This tests for a global Intl object, checks that it's not null and that it has a NumberFormat property that is a function.

Using locales

This example shows some of the variations in localized number formats. In order to get the format of the language used in the user interface of your application, make sure to specify that language (and possibly some fallback languages) using the locales argument:

const number = 123456.789;

// German uses comma as decimal separator and period for thousands
console.log(number.toLocaleString('de-DE'));
// → 123.456,789

// Arabic in most Arabic speaking countries uses Eastern Arabic digits
console.log(number.toLocaleString('ar-EG'));
// → ١٢٣٤٥٦٫٧٨٩

// India uses thousands/lakh/crore separators
console.log(number.toLocaleString('en-IN'));
// → 1,23,456.789

// the nu extension key requests a numbering system, e.g. Chinese decimal
console.log(number.toLocaleString('zh-Hans-CN-u-nu-hanidec'));
// → 一二三,四五六.七八九

// when requesting a language that may not be supported, such as
// Balinese, include a fallback language, in this case Indonesian
console.log(number.toLocaleString(['ban', 'id']));
// → 123.456,789

Using options

The results provided by toLocaleString can be customized using the options parameter:

const number = 123456.789;

// request a currency format
console.log(number.toLocaleString('de-DE', { style: 'currency', currency: 'EUR' }));
// → 123.456,79 €

// the Japanese yen doesn't use a minor unit
console.log(number.toLocaleString('ja-JP', { style: 'currency', currency: 'JPY' }))
// → ¥123,457

// limit to three significant digits
console.log(number.toLocaleString('en-IN', { maximumSignificantDigits: 3 }));
// → 1,23,000

// Use the host default language with options for number formatting
const num = 30000.65;
console.log(num.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}));
// → "30,000.65" where English is the default language, or
// → "30.000,65" where German is the default language, or
// → "30 000,65" where French is the default language

Specifications

Specification
ECMAScript Language Specification
# sec-number.prototype.tolocalestring
ECMAScript Internationalization API Specification
# sup-number.prototype.tolocalestring

Browser compatibility

BCD tables only load in the browser

See also