Intl.RelativeTimeFormat.prototype.format()

The Intl.RelativeTimeFormat.prototype.format() method formats a value and unit according to the locale and formatting options of this Intl.RelativeTimeFormat object.

Syntax

format(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.

Description

The function returned by the format getter formats a value and a unit into a string according to the locale and formatting options of this Intl.RelativeTimeFormat object.

Examples

Basic format usage

The following example shows how to create a relative time formatter using the English language.

// Create a relative time formatter in your locale
// with default values explicitly passed in.
const rtf = new Intl.RelativeTimeFormat("en", {
    localeMatcher: "best fit", // other values: "lookup"
    numeric: "always", // other values: "auto"
    style: "long", // other values: "short" or "narrow"
});

// Format relative time using negative value (-1).
rtf.format(-1, "day");
// > "1 day ago"

// Format relative time using positive  value (1).
rtf.format(1, "day");
// > "in 1 day"

Using the auto option

If numeric:auto option is passed, it will produce the string yesterday, today, or tomorrow instead of 1 day ago, in 0 days, or in 1 day. This allows to not always have to use numeric values in the output.

// Create a relative time formatter in your locale
// with numeric: "auto" option value passed in.
const rtf = new Intl.RelativeTimeFormat("en", { numeric: "auto" });

// Format relative time using negative value (-1).
rtf.format(-1, "day");
// > "yesterday"

rtf.format(0, "day");
// > "today"

// Format relative time using positive day unit (1).
rtf.format(1, "day");
// > "tomorrow"

Specifications

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

Browser compatibility

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See also