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

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

Syntax

dateTimeFormat.formatToParts(date)

Parameters

date Optional: The date to format.

Return value

An Array of objects containing the formatted date in parts.

Description

The formatToParts() method is useful for custom formatting of date 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: 'day', value: '17' },
  { type: 'weekday', value: 'Monday' }
]

Possible types are the following:

day: The string used for the day, for example "17".
dayPeriod: The string used for the day period, for example, "AM", "PM", "in the morning", or "noon"
era: The string used for the era, for example "BC" or "AD".
fractionalSecond: The string used for the fractional seconds, for example "0" or "00" or "000".
hour: The string used for the hour, for example "3" or "03".
literal: The string used for separating date and time values, for example "/", ",", "o'clock", "de", etc.
minute: The string used for the minute, for example "00".
month: The string used for the month, for example "12".
relatedYear: The string used for the related 4-digit Gregorian year, in the event that the calendar's representation would be a yearName instead of a year, for example "2019".
second: The string used for the second, for example "07" or "42".
timeZoneName: The string used for the name of the time zone, for example "UTC".
weekday: The string used for the weekday, for example "M", "Monday", or "Montag".
year: The string used for the year, for example "2012" or "96".
yearName: The string used for the yearName in relevant contexts, for example "geng-zi"

Polyfill

A polyfill for this feature is available in the proposal repository.

Examples

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

var date = Date.UTC(2012, 11, 17, 3, 0, 42);

var formatter = new Intl.DateTimeFormat('en-us', {
  weekday: 'long',
  year: 'numeric',
  month: 'numeric',
  day: 'numeric',
  hour: 'numeric',
  minute: 'numeric',
  second: 'numeric',
  fractionalSecondDigits: 3,
  hour12: true,
  timeZone: 'UTC'
});

formatter.format(date);
// "Monday, 12/17/2012, 3:00:42.000 AM"

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 DateTimeFormat formatters by providing you the string in parts:

formatter.formatToParts(date);

// return value: 
[ 
  { type: 'weekday',   value: 'Monday' }, 
  { type: 'literal',   value: ', '     }, 
  { type: 'month',     value: '12'     }, 
  { type: 'literal',   value: '/'      }, 
  { type: 'day',       value: '17'     }, 
  { type: 'literal',   value: '/'      }, 
  { type: 'year',      value: '2012'   }, 
  { type: 'literal',   value: ', '     }, 
  { type: 'hour',      value: '3'      }, 
  { type: 'literal',   value: ':'      }, 
  { type: 'minute',    value: '00'     }, 
  { type: 'literal',   value: ':'      }, 
  { type: 'second',    value: '42'     }, 
  { type: 'fractionalSecond', value: '000' },
  { type: 'literal',   value: ' '      }, 
  { type: 'dayPeriod', value: 'AM'     } 
]

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.join().

var dateString = formatter.formatToParts(date).map(({type, value}) => { 
  switch (type) {
    case 'dayPeriod': return `<b>${value}</b>`; 
    default : return value; 
  } 
}).join('');

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

console.log(formatter.format(date));
// "Monday, 12/17/2012, 3:00:42.000 AM"

console.log(dateString);
// "Monday, 12/17/2012, 3:00:42.000 <b>AM</b>"

Named Years and Mixed calendars

In some cases, calendars use named years. Chinese and Tibetan calendars, for example, use a 60-year sexagenary cycle of named years. These years are disambiguated by relationship to corresponding years on the Gregorian calendar. When this is the case, the result of formatToParts() will contain an entry for relatedYear when a year would normally be present, containing the 4-digit Gregorian year, instead of an entry for year. Setting an entry in the bag for year (with any value) will yield both the and the yearName Gregorian relatedYear:

let opts = { year: "numeric", month: "numeric", day: "numeric" };
let df = new Intl.DateTimeFormat("zh-u-ca-chinese", opts);
df.formatToParts(Date.UTC(2012, 11, 17, 3, 0, 42));

// return value
[
  { type: 'relatedYear', value: '2012' },
  { type: 'literal', value: '年' },
  { type: 'month', value: '十一月' },
  { type: 'day', value: '4' }
]

If the year option is not set in the bag (to any value), the result will include only the relatedYear:

let df = new Intl.DateTimeFormat("zh-u-ca-chinese");
df.formatToParts(Date.UTC(2012, 11, 17, 3, 0, 42));

// return value
[
   { type: 'relatedYear', value: '2012' },
   { type: 'literal', value: '年' },
   { type: 'month', value: '十一月' },
   { type: 'day', value: '4' } 
]

In cases where the year would be output, .format() may commonly present these side-by-side:

let df = new Intl.DateTimeFormat("zh-u-ca-chinese", {year: "numeric"});
df.format(Date.UTC(2012, 11, 17, 3, 0, 42));

// return value
2012壬辰年

This also makes it possible to mix locale and calendar in both format:

let df = new Intl.DateTimeFormat("en-u-ca-chinese", {year: "numeric"});
let date = Date.UTC(2012, 11, 17, 3, 0, 42);
df.format(date);

// return value
2012(ren-chen)

And formatToParts:

let opts = {month: 'numeric', day: 'numeric', year: "numeric"};
let df = new Intl.DateTimeFormat("en-u-ca-chinese", opts);
let date = Date.UTC(2012, 11, 17, 3);
df.formatToParts(date)

// return value
[
  { type: 'month', value: '11' },
  { type: 'literal', value: '/' },
  { type: 'day', value: '4' },
  { type: 'literal', value: '/' },
  { type: 'relatedYear', value: '2012' }
]

Specifications

Specification
ECMAScript Internationalization API (ECMA-402)The definition of 'Intl.DateTimeFormat.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`	Chrome Full support 57 Notes' Full support 57 Notes' Notes' Before version 71, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 71 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	Edge Full support 18	Firefox Full support 51	IE No support No	Opera Full support 44 Notes' Full support 44 Notes' Notes' Before version 58, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 58 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	Safari Full support 11	WebView Android Full support 57 Notes' Full support 57 Notes' Notes' Before version 71, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 71 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	Chrome Android Full support 57 Notes' Full support 57 Notes' Notes' Before version 71, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 71 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	Firefox Android Full support 56	Opera Android Full support 43 Notes' Full support 43 Notes' Notes' Before version 50, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 50 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	Safari iOS Full support 11	Samsung Internet Android Full support 7.0 Notes' Full support 7.0 Notes' Notes' Before version 71, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 71 and later use the specification defined `dayPeriod`. See Chromium bug 865351.	nodejs Full support 8.0.0 Notes' Full support 8.0.0 Notes' Notes' Before version 12.0.0, `formatToParts()` returned an object with an incorrectly cased type key of `dayperiod`. Version 12.0.0 and later use the specification defined `dayPeriod`. See Chromium bug 865351. Notes' Before version 13.0.0, only the locale data for `en-US` is available by default. See the `DateTimeFormat()` constructor for more details.

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.