Intl.RelativeTimeFormat() constructor

The Intl.RelativeTimeFormat() constructor creates Intl.RelativeTimeFormat objects.

locales Optional

A string with a BCP 47 language tag, or an array of such strings. For the general form and interpretation of the locales argument, see the Intl page.

options Optional

An object with some or all of the following properties:

localeMatcher

The locale matching algorithm to use. Possible values are "lookup" and "best fit"; the default is "best fit". For information about this option, see the Intl page.

numeric

The format of output message. Possible values are:

• "always" (default, e.g., 1 day ago),
• or "auto" (e.g., yesterday). The "auto" value allows to not always have to use numeric values in the output.

style

The length of the internationalized message. Possible values are:

• "long" (default, e.g., in 1 month)
• "short" (e.g., in 1 mo.),
• or "narrow" (e.g., in 1 mo.). The narrow style could be similar to the short style for some locales.

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"

If numeric:auto option is passed, it will produce the string yesterday or tomorrow instead of 1 day ago 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"

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

• Intl.RelativeTimeFormat
• Intl
• The Intl.RelativeTimeFormat API