Web/JavaScript/Reference/Global objects/Intl/NumberFormat/formatToParts

The Intl.Numberformat.prototype.formatToParts() method allows locale-aware formatting of strings produced by NumberFormat 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 ("%").
unit: The unit string, such as the "l" or "litres", depending on how unitDisplay is specified.

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

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`formatToParts` Experimental'	Chrome Full support 64	Edge Full support 12	Firefox Full support 58	IE No support No	Opera Full support 51	Safari Full support 13	WebView Android Full support 64	Chrome Android Full support 64	Firefox Android Full support 58	Opera Android Full support 47	Safari iOS Full support 13	Samsung Internet Android Full support 9.0	nodejs 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.