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.
Try it
const rtf1 = new Intl.RelativeTimeFormat("en", { numeric: "auto" });
const parts = rtf1.formatToParts(10, "seconds");
console.log(parts[0].value);
// Expected output: "in "
console.log(parts[1].value);
// Expected output: "10"
console.log(parts[2].value);
// Expected output: " seconds"
Syntax
formatToParts(value, unit)
Parameters
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® 2025 Internationalization API Specification # sec-Intl.RelativeTimeFormat.prototype.formatToParts |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
formatToParts |
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- See implementation notes.