The toString() method of Temporal.Duration instances returns a string representing this duration in the ISO 8601 format.

Syntax

toString()
toString(options)

Parameters

options Optional

An object containing some or all of the following properties (in the order they are retrieved and validated):

fractionalSecondDigits Optional

Either an integer from 0 to 9, or the string "auto". The default is "auto". If "auto", then trailing zeros are removed from the fractional seconds. Otherwise, the fractional part of the second component contains this many digits, padded with zeros or rounded as necessary.

roundingMode Optional

A string specifying how to round off fractional second digits beyond fractionalSecondDigits. See Intl.NumberFormat(). Defaults to "trunc".

smallestUnit Optional

A string specifying the smallest unit to include in the output. Possible values are "second", "millisecond", "microsecond", and "nanosecond", or their plural forms, which are equivalent to fractionalSecondDigits values of 0, 3, 6, 9, respectively. If specified, then fractionalSecondDigits is ignored.

Return value

A string representing the given duration in the ISO 8601 format, with subsecond components formatted according to the options. The zero duration is represented as "PT0S".

Exceptions

RangeError

Thrown if any of the options is invalid.

Examples

Using toString()

const duration = Temporal.Duration.from({ hours: 1, minutes: 30, seconds: 15 });
console.log(duration.toString()); // 'PT1H30M15S'

// Stringification implicitly calls toString()
console.log(`${duration}`); // 'PT1H30M15S'

Using options

const worldRecord = Temporal.Duration.from({ seconds: 9, milliseconds: 580 });
console.log(worldRecord.toString()); // 'PT9.58S'
console.log(worldRecord.toString({ fractionalSecondDigits: 1 })); // 'PT9.5S'
console.log(worldRecord.toString({ fractionalSecondDigits: 0 })); // 'PT9S'
console.log(worldRecord.toString({ smallestUnit: "millisecond" })); // 'PT9.580S'
console.log(
  worldRecord.toString({
    fractionalSecondDigits: 1,
    roundingMode: "halfExpand",
  }),
); // 'PT9.6S'

Specifications

Browser compatibility

See also

• Temporal.Duration
• Temporal.Duration.prototype.toJSON()
• Temporal.Duration.prototype.toLocaleString()