Intl.NumberFormat.prototype.formatToParts()

The Intl.Numberformat.prototype.formatToParts() method allows locale-aware formatting of strings produced by NumberTimeFormat formatters.

Syntax

Intl.NumberFormat.prototype.formatToParts(number)

Parameters

number Optional
A Number or BigInt to format.

Return value

An Array of objects containing the formatted number in parts.

Description

The formatToParts() method is useful for custom formatting of number strings. It returns an Array of objects containing the locale-specific tokens from which it possible to build custom strings while preserving the locale-specific parts. The structure the formatToParts() method returns, looks like this:

[
  { type: "integer", value: "3" },
  { type: "group", value: "." },
  { type: "integer", value: "500" }
]

Possible types are the following:

currency
The currency string, such as the symbols "$" and "€" or the name "Dollar", "Euro" depending on how currencyDisplay is specified.
decimal
The decimal separator string (".").
fraction
The fraction number.
group
The group separator string (",").
infinity
The Infinity string ("∞").
integer
The integer number.
literal
Any literal strings or whitespace in the formatted number.
minusSign
The minus sign string ("-").
nan
The NaN string ("NaN").
plusSign
The plus sign string ("+").
percentSign
The percent sign string ("%").

Examples

Comparing format and formatToParts

NumberFormat outputs localized, opaque strings that cannot be manipulated directly:

var number = 3500;

var formatter = new Intl.NumberFormat('de-DE', { 
  style: 'currency', 
  currency: 'EUR' 
});

formatter.format(number);
// "3.500,00 €"

However, in many User Interfaces there is a desire to customize the formatting of this string. The formatToParts method enables locale-aware formatting of strings produced by NumberFormat formatters by providing you the string in parts:

formatter.formatToParts(number);

// return value: 
[ 
  { type: "integer",  value: "3"   },
  { type: "group",    value: "."   },
  { type: "integer",  value: "500" },
  { type: "decimal",  value: ","   },
  { type: "fraction", value: "00"  },
  { type: "literal",  value: " "   },
  { type: "currency", value: "€"   }
]

Now the information is available separately and it can be formatted and concatenated again in a customized way. For example by using Array.prototype.map(), arrow functions, a switch statement, template literals, and Array.prototype.reduce().

var numberString = formatter.formatToParts(number).map(({type, value}) => { 
  switch (type) {
    case 'currency': return `<strong>${value}</strong>`; 
    default : return value; 
  } 
}).reduce((string, part) => string + part);

This will make the currency bold, when using the formatToParts() method.

console.log(numberString);
// "3.500,00 <strong>€</strong>"

Specifications

Specification
ECMAScript Internationalization API (ECMA-402)
The definition of 'Intl.NumberFormat.prototype.formatToParts' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
formatToParts
Experimental
Chrome Full support 64Edge Full support 12Firefox Full support 58IE No support NoOpera Full support 51Safari Full support 13WebView Android Full support 64Chrome Android Full support 64Firefox Android Full support 58Opera Android Full support 47Safari iOS Full support 13Samsung Internet Android Full support 9.0nodejs Full support 10.0.0
Notes
Full support 10.0.0
Notes
Notes Before version 13.0.0, only the locale data for en-US is available by default. See the NumberFormat() constructor for more details.

Legend

Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.

See also