Number.prototype.toLocaleString()
The toLocaleString()
method returns a string with a language-sensitive representation of this number. In implementations with Intl.NumberFormat
API support, this method simply calls Intl.NumberFormat
.
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 that support the Intl.NumberFormat
API, these parameters correspond exactly to the Intl.NumberFormat()
constructor's parameters. Implementations without Intl.NumberFormat
support are asked to ignore both parameters, making the locale used and the form of the string returned entirely implementation-dependent.
locales
Optional-
A string with a BCP 47 language tag, or an array of such strings. Corresponds to the
locales
parameter of theIntl.NumberFormat()
constructor.In implementations without
Intl.NumberFormat
support, this parameter is ignored and the host's locale is usually used. options
Optional-
An object adjusting the output format. Corresponds to the
options
parameter of theIntl.NumberFormat()
constructor.In implementations without
Intl.NumberFormat
support, this parameter is ignored.
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.
In implementations with Intl.NumberFormat
, this is equivalent to new Intl.NumberFormat(locales, options).format(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()); // "3,500" if in U.S. English locale
Checking for support for locales and options arguments
Not all implementations are required to support ECMA-402 (the Internationalization API). For those that don't, the locales
and options
arguments must both be ignored. You can check support by testing if illegal language tags are rejected with a RangeError
:
function toLocaleStringSupportsLocales() {
const number = 0;
try {
number.toLocaleString('i');
} catch (e) {
return e.name === 'RangeError';
}
return false;
}
However, prior to ES5.1, implementations were not required to throw a range error exception if toLocaleString
is called with illegal 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