Intl.RelativeTimeFormat.prototype.formatToParts()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2020.

The formatToParts() method of Intl.RelativeTimeFormat instances returns an array of objects representing each part of the formatted string that would be returned by format(). It is useful for building custom strings from the locale-specific tokens.

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Syntax

formatToParts(value, unit)

Parameters

value: Numeric value to use in the internationalized relative time message.
unit: Unit to use in the relative time internationalized message. Possible values are: "year", "quarter", "month", "week", "day", "hour", "minute", "second". Plural forms are also permitted.

Return value

An Array of objects containing the formatted relative time in parts. Each object has two or three properties, type, value, and optionally unit, each containing a string. The string concatenation of value, in the order provided, will result in the same string as format(). The parts can be thought of as directly obtained from calling Intl.NumberFormat.prototype.formatToParts() with the numeric value, passing only the numberingSystem option, and then adding additional type: "literal" tokens, such as "in ", " days ago", etc. All tokens that are produced by the NumberFormat have an additional unit property, which is the singular form of the input unit; this is for programmatic usage and is not localized. The localized unit is output as a part of a literal token.

When options.numeric is "auto", and there's a special string for the value, the returned array is a single literal token.

Examples

Using formatToParts()

const rtf = new Intl.RelativeTimeFormat("en", { numeric: "auto" });

// Format relative time using the day unit
rtf.formatToParts(-1, "day");
// [{ type: "literal", value: "yesterday"}]

rtf.formatToParts(100, "day");
// [
//   { type: "literal", value: "in " },
//   { type: "integer", value: "100", unit: "day" },
//   { type: "literal", value: " days" }
// ]

Specifications

Specification
ECMAScript Internationalization API Specification # sec-Intl.RelativeTimeFormat.prototype.formatToParts

Browser compatibility

	Desktop					Mobile						Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	Deno	Node.js
`formatToParts`	71	79	70	58	14	71	79	50	14	10.0	71	1.8	12.0.0 Before version 13.0.0, only the locale data for `en-US` is available by default. See the `RelativeTimeFormat()` constructor for more details.