The Intl.RelativeTimeFormat.prototype.formatToParts() method returns an Array of objects representing the relative time format in parts that can be used for custom locale-aware formatting.


RelativeTimeFormat.formatToParts(value, unit)


Numeric value to use in the internationalized relative time message.
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.


The Intl.RelativeTimeFormat.prototype.formatToParts method is a version of the format method which it returns an array of objects which represent "parts" of the object, separating the formatted number into its consituent parts and separating it from other surrounding text. These objects have two properties: type a NumberFormat formatToParts type, and value, which is the String which is the component of the output. If a "part" came from NumberFormat, it will have a unit property which indicates the unit being formatted; literals which are part of the larger frame will not have this property.


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" }]


Specification Status Comment
ECMAScript Internationalization API (ECMA-402)
The definition of 'RelativeTimeFormat.formatToParts()' in that specification.
Stage 4

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
formatToPartsChrome Full support 71Edge Full support 79Firefox Full support 70IE No support NoOpera Full support 58Safari Full support 14WebView Android Full support 71Chrome Android Full support 71Firefox Android No support NoOpera Android Full support 50Safari iOS Full support 14Samsung Internet Android Full support 10.0nodejs Full support 12.0.0
Full support 12.0.0
Notes Before version 13.0.0, only the locale data for en-US is available by default. See the RelativeTimeFormat() constructor for more details.


Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

See also