Number.prototype.toLocaleString()

Summary

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

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

Syntax

numObj.toLocaleString([locales [, options]])

Parameters

Check the Browser compatibility section to see which browsers support the locales and options arguments, and the Example: Checking for support for locales and options arguments for feature detection.

locales

A string with a BCP 47 language tag, or an array of such strings. For the general form and interpretation of the locales argument, see the Intl page. The following Unicode extension key is allowed:

nu

The numbering system to be used. Possible values include: "arab", "arabext", "bali", "beng", "deva", "fullwide", "gujr", "guru", "hanidec", "khmr", "knda", "laoo", "latn", "limb", "mlym", "mong", "mymr", "orya", "tamldec", "telu", "thai", "tibt".

options

An object with some or all of the following properties:

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. Possible values are "decimal" for plain number formatting, "currency" for currency formatting, and "percent" for percent formatting; the default is "decimal".

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 €, "code" to use the ISO currency code, "name" to use a localized currency name such as "dollar"; the default is "symbol".

useGrouping

Whether to use grouping separators, such as thousands separators or thousand/lakh/crore separators. Possible values are true and false; the default is true.

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 minimumSignificantDigits.

Examples

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

var number = 3500;

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

Example: Checking for support for locales and options arguments

The locales and options arguments are not supported in all browsers yet. To check whether an implementation supports them already, you can use the requirement that illegal language tags are rejected with a RangeError exception:

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

Example: 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:

var number = 123456.789;

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

// Arabic in most Arabic speaking countries uses real Arabic digits
alert(number.toLocaleString("ar-EG"));
// → ١٢٣٤٥٦٫٧٨٩

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

// the nu extension key requests a numbering system, e.g. Chinese decimal
alert(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
alert(number.toLocaleString(["ban", "id"]));
// → 123.456,789

Example: Using options

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

var number = 123456.789;

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

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

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

Performance

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

Specifications

Browser compatibility

See also

• Number.prototype.toString()