piso

ISO 8601 date, duration, and interval parsing package as declared on Wikipedia ISO 8601.

In Spain, piso refers to the whole apartment, whereas in Mexico, it refers only to the floor of your departamento. But the above has nothing to do with this project.

Api

`parseInterval(iso8601Interval[, enforceUTC])`

Parse interval from an ISO 8601 interval string.

iso8601Interval: string with ISO 8601 interval source
enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Returns ISOInterval.

Interval sources are bounded by their field limits: repetitions accept at most 17 digits, a maximal date — signed 17 digit year, 17 second fractions, and offset with seconds — is 60 characters, and a maximal duration is 129 characters. Consequently a valid interval never exceeds 209 characters.

import { parseInterval, ISOInterval } from '@0dep/piso';

const viableIntervals = [
  '2007-03-01/2007-04-01',
  'P2Y/2007-03-01T13:00:00Z',
  '2007-03-01T13:00:00Z/P2Y',
  'R5/P1Y/2025-05-01T13:00:00Z',
  'R-1/2009-07-01T00:00Z/P1M',
  'R-1/1972-07-01T00:02Z/PT1H3M',
  'R-1/P1M/2024-07-27T00:00Z',
  '2007-318/2007-319',
  '2007-318/319T24:00:00Z',
  '2026-09-01T10:00:00Z',
];

for (const i of viableIntervals) {
  console.log({ [i]: parseInterval(i).getExpireAt(), utc: parseInterval(i, true).getExpireAt() });
}

`parseDuration(iso8601Duration)`

Parse duration from an ISO 8601 duration string.

iso8601Duration: string with ISO 8601 duration source

Returns ISODuration.

Interval sources are accepted as well, e.g. R3/PT10H or 2007-03-01/P1Y, in which case the duration part is returned.

Each duration designator value accepts at most 17 digits, so a valid duration never exceeds 129 characters — more throws RangeError.

A leading minus (- or unicode minus −) as of ISO 8601-2:2019 negates the duration, e.g. -P1D, and is only accepted by parseDuration and ISODuration — not in intervals. The parsed result then has sign: -1, getExpireAt subtracts the duration and getStartAt adds it.

Years and months are calendar units, so when the start day does not exist in the target month the day is clamped to the last day of that month, as in Temporal and luxon: January 31 plus P1M is February 28, February 29 plus P1Y is February 28. Repetitions count from the original day, so the third month from January 31 is April 30 and not April 28, and a day designator is added after the clamped month, so January 31 plus P1M1D is March 1.

import { parseDuration } from '@0dep/piso';

const monthly = parseDuration('P1M');
const start = new Date(Date.UTC(2021, 0, 31));

console.log(monthly.getExpireAt(start).toISOString());
// 2021-02-28T00:00:00.000Z
console.log(monthly.getExpireAt(start, 3).toISOString());
// 2021-04-30T00:00:00.000Z

const leapDay = new Date(Date.UTC(2024, 1, 29));

console.log(parseDuration('P1Y').getExpireAt(leapDay).toISOString());
// 2025-02-28T00:00:00.000Z

import { parseDuration } from '@0dep/piso';

const yesterday = parseDuration('-P1D');

console.log(yesterday.result.sign, yesterday.getExpireAt(new Date(Date.UTC(2024, 2, 1))).toISOString());

import { parseDuration } from '@0dep/piso';

const viableDurations = [
  'PT1M5S',
  'PT1M0.5S',
  'PT0.5S',
  'PT0.01S',
  'PT0.001S',
  'PT0.0001S',
  'PT0.5M',
  'PT0.5H',
  'PT1.5H',
  'P0.5D',
  'P1W',
  'P0.5W',
  'P0.5M',
  'P0.5D',
  'P1Y',
  'P1Y2M3W4DT5H6M7S',
  'PT0S',
  'P0D',
];

for (const d of viableDurations) {
  console.log({ [d]: parseDuration(d).getExpireAt() });
}

try {
  // fractions are only allowed on the smallest unit
  parseDuration('P0.5YT3S');
} catch (err) {
  console.log({ err });
}

`getDate(iso8601Date[, enforceUTC])`

Get Date from an ISO 8601 date time string.

iso8601Date: string with ISO 8601 date source, date and number are also accepted
enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Returns date.

import { getDate } from '@0dep/piso';

const viableDates = [
  '2024-01-27',
  '2024-02-28',
  '2024-02-29',
  '2020-02-29',
  '2016-02-29',
  '2024-W03-2',
  '2024-01',
  '2024-12',
  '20240127',
  '2024-012',
  '2024012',
  '2024-012T08:06:30',
  '2024-02-27T08:06:30',
  '2024-02-27T08:06:30.001',
  '2024-02-27T08:06:30.0011',
  '2024-02-27T08:06:30.0',
  '2024-02-27T08:06:30,001',
  '2024-02-27T08:06:30Z',
  '2024-02-03T08:06:30+02:00',
  '2024-02-03T08:06:30.5+02:00',
  '20240203T080630+0200',
  '2024-02-03T08:06:30-02:30',
  '2024-02-03T08:06:30-02',
  '2025-01-01T12:00:42.01-02:00',
  '2025-01-01T12:00:42.01+02:30',
  '2025-01-01T12:00:42.01+02:30:30',
  '2025-01-01T23:59',
  '2025-01-01T24:00',
  '2025-01-01T24:00:00',
  '2025-01-01T24:00:00.000',
  '2025-01-01T24:00Z',
  '2025-01-01T24:00+01',
  '2025-01-01T24:00:00+01',
  '2025-01-01T24:00:00.00+01',
  '20240127T1200',
  '20240127T120001',
  '20240127T120001,001',
  '2024',
  '+102024',
  '-00000012',
  new Date(2024, 3, 22),
  0,
  Date.UTC(2024, 3, 22),
];

for (const d of viableDates) {
  console.log({ [d]: getDate(d), utc: getDate(d, true) });
}

try {
  getDate('2023-02-29');
} catch (err) {
  console.log({ err });
}

try {
  // not this year
  getDate('2023-W53-1T12:00');
} catch (err) {
  console.log({ err });
}

try {
  // unbalanced separators
  getDate('2023-02-28T1200');
} catch (err) {
  console.log({ err });
}

NB! string without timezone precision is considered local date, or as Wikipedia put it "If no UTC relation information is given with a time representation, the time is assumed to be in local time". Unless, of course, enforce UTC instruction is used.

`getExpireAt(iso8601Interval[, compareDate[, startDate[, enforceUTC]]])`

Parse interval and get the closest expire at date, see interval.getExpireAt.

iso8601Interval: string with ISO 8601 interval source
compareDate: optional date that repetitions are compared against, defaults to now
startDate: optional start date, used when the source is a duration without start or end date, defaults to now
enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Returns date.

import { getExpireAt } from '@0dep/piso';

console.log(getExpireAt('R-1/2024-01-01T00:00Z/P1M', new Date(Date.UTC(2024, 2, 15))).toISOString());
// 2024-04-01T00:00:00.000Z

console.log(getExpireAt('PT1H', undefined, new Date(Date.UTC(2024, 0, 1))).toISOString());
// 2024-01-01T01:00:00.000Z

`getStartAt(iso8601Interval[, compareDate[, endDate[, enforceUTC]]])`

Parse interval and get the start at date, see interval.getStartAt.

iso8601Interval: string with ISO 8601 interval source
compareDate: optional date that repetitions are compared against, defaults to now
endDate: optional end date, used when the source is a duration without start or end date, defaults to now
enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Returns date.

import { getStartAt } from '@0dep/piso';

console.log(getStartAt('R-1/P1M/2024-12-01T00:00Z', new Date(Date.UTC(2024, 2, 15))).toISOString());
// 2024-11-01T00:00:00.000Z

`getUTCLastWeekOfYear(Y)`

Get last week of year

Y: full year

Returns 52 or 53.

import { getUTCLastWeekOfYear } from '@0dep/piso';

console.log('last week number', getUTCLastWeekOfYear(2024));

`getUTCWeekOneDate(Y)`

Get Monday week one date

Y: full year

Returns date Monday week one

import { getUTCWeekOneDate } from '@0dep/piso';

console.log('Monday week one', getUTCWeekOneDate(2021));

`getISOWeekString([date])`

Get ISO week date string from date.

date: optional date, defaults to now

import { getISOWeekString } from '@0dep/piso';

console.log('date as week', getISOWeekString(new Date(2021, 11, 28)));

`getUTCWeekNumber([date])`

Get weeknumber from date.

date: optional date, defaults to now

Returns:

Y: full year representation of week date
W: week number
weekday: ISO weekday, 1 = Monday .. 7 = Sunday

import { getUTCWeekNumber } from '@0dep/piso';

console.log(getUTCWeekNumber(new Date(2016, 0, 1)));

`new ISOInterval(source[, enforceUTC])`

Interval instance.

Constructor:

source: ISO8601 interval source
enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Properties:

repeat: number of repeats
start: start date as ISODate
duration: duration as ISODuration
end: end date as ISODate
type: interval type
get startDate: start date as date, requires parse() to be called
get endDate: end date as date, requires parse() to be called

`interval.type`

Number representing the interval type flags. Available after parse.

1: Repeat
2: Start date
4: Duration
8: End date

Example flags

2: Start date only, a point in time where start and expire dates coincide
3: Repeat and start date, rather pointless but possible nevertheless
5: Repeat and duration
6: Start date and duration
7: Repeat, start date, and duration
10: Start- and end date
12: Duration and end date
13: Repeat, duration, and end date

Do I have repeat in my interval?

import { parseInterval } from '@0dep/piso';

console.log((parseInterval('R3/P1Y').type & 1) === 1 ? 'Yes' : 'No');
// Yes

console.log((parseInterval('R-1/P1Y').type & 1) === 1 ? 'Yes' : 'No');
// Yes, indefinite number of repetitions

console.log((parseInterval('R-1/2024-03-27/P1Y').type & 1) === 1 ? 'Yes' : 'No');
// Yes, indefinite number of repetitions from start date

console.log((parseInterval('R-1/P1Y/2024-03-27').type & 1) === 1 ? 'Yes' : 'No');
// Yes, indefinite number of repetitions until end date

console.log((parseInterval('R0/P1Y').type & 1) === 1 ? 'Yes' : 'No');
// No, zero is equal to once

console.log((parseInterval('R1/P1Y').type & 1) === 1 ? 'Yes' : 'No');
// No, since it's just once

console.log((parseInterval('R1/2024-03-28').type & 1) === 1 ? 'Yes' : 'No');
// No, pointless repeat

console.log((parseInterval('R1/2024-03-28/31').type & 1) === 1 ? 'Yes' : 'No');
// No, pointless repeat

console.log((parseInterval('R1/P1Y/2024-03-28').type & 1) === 1 ? 'Yes' : 'No');
// No

Is start date defined in my interval?

import { parseInterval } from '@0dep/piso';

const interval = parseInterval('R-1/2024-03-28/P1Y');

console.log((interval.type | 2) === interval.type ? 'Yes' : 'No');

Start date only

An interval consisting of only a start date is a point in time, start and expire dates are the same.

import { parseInterval } from '@0dep/piso';

const interval = parseInterval('2026-09-01T10:00:00Z');

console.log(interval.type);
// 2

console.log(interval.getStartAt().toISOString());
// 2026-09-01T10:00:00.000Z

console.log(interval.getExpireAt().toISOString());
// 2026-09-01T10:00:00.000Z

`interval.parse()`

Returns ISOInterval.

Throws RangeError if something is off.

`interval.getExpireAt([compareDate[, startDate[, enforceUTC]]])`

Get the closest expire at date. Parses the source if parse() has not been called.

compareDate: optional date that repetitions are compared against, defaults to now
startDate: optional start date, used when the interval is a duration without start or end date, defaults to now
enforceUTC: optional boolean, overrides the constructor argument

Returns date.

A repeating interval walks the repetitions forward from the start date, or backward from the end date, and returns the first expire date after compareDate. An interval with an end date and no repeat returns the end date, and an interval with only a start date returns the start date.

import { parseInterval } from '@0dep/piso';

const interval = parseInterval('R-1/2024-01-01T00:00Z/P1M');

console.log(interval.getExpireAt(new Date(Date.UTC(2024, 2, 15))).toISOString());
// 2024-04-01T00:00:00.000Z

`interval.getStartAt([compareDate[, endDate[, enforceUTC]]])`

Get the start at date. Parses the source if parse() has not been called.

compareDate: optional date that repetitions are compared against, defaults to now
endDate: optional end date, used when the interval is a duration without start or end date, defaults to now
enforceUTC: optional boolean, overrides the constructor argument

Returns date.

A repeating interval returns the start of the repetition that expires first after compareDate. An interval with a start date and no repeat returns the start date.

import { parseInterval } from '@0dep/piso';

const interval = parseInterval('R-1/2024-01-01T00:00Z/P1M');

console.log(interval.getStartAt(new Date(Date.UTC(2024, 2, 15))).toISOString());
// 2024-03-01T00:00:00.000Z

`interval.toJSON()`

Get interval represented as JavaScript Object Notation.

import { ISOInterval } from '@0dep/piso';

console.log(JSON.stringify({ interval: new ISOInterval('R2/P1Y/2024-03-28') }, null, 2));

`new ISODate(source[, options])`

ISO date instance.

Constructor:

source: ISO 8601 date source string
options: optional parsing options
- offset: source string offset column number, -1 is default
- endChars: string with optional characters that mark the end of the ISO date, e.g. /
- enforceSeparators: boolean that will require time part separators such as - and :
- enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

Properties:

result:
- Y: full year
- M: javascript month
- D: date or ordinal day
- H: hours
- m: minutes
- S: seconds
- F: milliseconds, including fractional milliseconds when the source has more than 3 fraction digits; at most 17 fraction digits are accepted, more throws RangeError
- Z: Z, +, −, or -
- OH: offset hours
- Om: offset minutes
- OS: offset seconds
- isValid: boolean indicating if parse was successful

`date.parse()`

Parse the source and populate result. Returns ISODate.

Throws RangeError if something is off.

`date.parsePartialDate(Y, M, D, W)`

Parse partial date as compared to passed date part arguments.

Y: required full year
M: optional javascript month, required is not ordinal day
D: required date, weekday (1 = Monday .. 7 = Sunday) if W is passed, or ordinal day
W: optional week number, then D is the week day

Returns ISODate

`date.toDate([enforceUTC])`

Get Date represented by source.

enforceUTC: optional boolean, enforce UTC if source lacks time zone offset

`date.toJSON()`

Get Date represented as JavaScript Object Notation.

`new ISODuration(source[, offset])`

Duration instance.

Constructor:

source: duration source string
offset: optional source string offset column number

Properties:

result:
- Y: years
- M: months
- W: weeks
- D: days
- H: hours
- m: minutes
- S: seconds
- sign: -1 if the source has a leading minus, otherwise absent
- isValid: boolean indicating if parse was successful

`duration.parse()`

Parse the source and populate result. Returns ISODuration.

Throws RangeError if something is off.

`duration.getExpireAt([startDate[, repetition]])`

Get the date the duration expires at, applied in UTC. A negative duration subtracts instead. Years and months clamp the day to the target month, see parseDuration.

startDate: optional start date, defaults to now
repetition: optional number of times to apply the duration, defaults to 1

Returns date.

import { parseDuration } from '@0dep/piso';

const duration = parseDuration('PT2H30M');

console.log(duration.getExpireAt(new Date(Date.UTC(2024, 0, 1)), 2).toISOString());
// 2024-01-01T05:00:00.000Z

`duration.getStartAt([endDate[, repetition]])`

Get the date the duration started at, i.e. the duration subtracted from the end date in UTC. A negative duration adds instead.

endDate: optional end date, defaults to now
repetition: optional number of times to apply the duration, defaults to 1

Returns date.

`duration.toMilliseconds([startDate[, repetition]])`

Get duration in milliseconds from optional start date.

startDate: optional start date, defaults to 1971-01-01T00:00:00Z since it is not a leap year
repetition: optional number of times to apply the duration, defaults to 1

`duration.untilMilliseconds([endDate[, repetition]])`

Get duration in milliseconds until optional end date, hence a negative number for a positive duration.

endDate: optional end date, defaults to 1971-01-01T00:00:00Z
repetition: optional number of times to apply the duration, defaults to 1

Example

An example to get start and end date:

import { parseInterval } from '@0dep/piso';

const source = '2007-03-01T13:00:00Z/P1Y2M10DT2H30M';

const interval = parseInterval(source);

console.log('starts at', interval.getStartAt());
console.log('expires at', interval.getExpireAt());
console.log('duration milliseconds', interval.duration.toMilliseconds());

An example to get duration milliseconds:

import { parseDuration } from '@0dep/piso';

const duration = parseDuration('PT2H30M');

console.log('duration milliseconds', duration.toMilliseconds(new Date()));

Repetitions

With end date

R4/P2Y/2007-08-01

Repetition	start at	expire at
4	1999-08-01	2001-08-01
3	2001-08-01	2003-08-01
2	2003-08-01	2005-08-01
1	2005-08-01	2007-08-01

Benchmarking

On Node 26 piso parses intervals 4.1–7.7 times and dates 4.5–4.6 times faster than luxon, and durations 1.2–2.5 times faster than luxon and iso8601-duration. Native new Date is still 2.4–3.1 times faster than piso, and the native Temporal that ships with Node 26 parses dates about twice as fast as piso while piso stays ahead on fractional durations and duration arithmetic. What piso does that neither native Date nor the RegExp-based libraries do is tell you where a malformed string went wrong:

import { parseInterval } from '@0dep/piso';

try {
  parseInterval('R5/2024-01-01T00:00Z/P1Y2M10DT2H3OM');
} catch (err) {
  console.log(err.message);
  // Unexpected ISO 8601 duration character "R5/2024-01-01T00:00Z/P1Y2M10DT2H3[O]" at 33
}

try {
  parseInterval('R5/2024-02-30T00:00Z/P1Y');
} catch (err) {
  console.log(err.message);
  // ISO 8601 date day "R5/2024-02-30[T]" at 13 is out of range 1-29
}

Throughput tables, the capability and error message comparison against luxon, iso8601-duration, and temporal, and how to run the suites are in bench/README.md. The numbers there come from executed npm run bench and npm run compare runs and note the Node version, since the margins over the RegExp-based libraries shift between V8 versions.

Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
bench		bench
src		src
test		test
types		types
.gitignore		.gitignore
.mocharc.json		.mocharc.json
.nvmrc		.nvmrc
.prettierignore		.prettierignore
.prettierrc.json		.prettierrc.json
AGENTS.md		AGENTS.md
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
eslint.config.js		eslint.config.js
package.json		package.json
rollup.config.js		rollup.config.js
tsconfig.json		tsconfig.json

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piso

Contents

Api

parseInterval(iso8601Interval[, enforceUTC])

parseDuration(iso8601Duration)

getDate(iso8601Date[, enforceUTC])

getExpireAt(iso8601Interval[, compareDate[, startDate[, enforceUTC]]])

getStartAt(iso8601Interval[, compareDate[, endDate[, enforceUTC]]])

getUTCLastWeekOfYear(Y)

getUTCWeekOneDate(Y)

getISOWeekString([date])

getUTCWeekNumber([date])

new ISOInterval(source[, enforceUTC])

interval.type

interval.parse()

interval.getExpireAt([compareDate[, startDate[, enforceUTC]]])

interval.getStartAt([compareDate[, endDate[, enforceUTC]]])

interval.toJSON()

new ISODate(source[, options])

date.parse()

date.parsePartialDate(Y, M, D, W)

date.toDate([enforceUTC])

date.toJSON()

new ISODuration(source[, offset])

duration.parse()

duration.getExpireAt([startDate[, repetition]])

duration.getStartAt([endDate[, repetition]])

duration.toMilliseconds([startDate[, repetition]])

duration.untilMilliseconds([endDate[, repetition]])

Example

Repetitions

With end date

Benchmarking

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`parseInterval(iso8601Interval[, enforceUTC])`

`parseDuration(iso8601Duration)`

`getDate(iso8601Date[, enforceUTC])`

`getExpireAt(iso8601Interval[, compareDate[, startDate[, enforceUTC]]])`

`getStartAt(iso8601Interval[, compareDate[, endDate[, enforceUTC]]])`

`getUTCLastWeekOfYear(Y)`

`getUTCWeekOneDate(Y)`

`getISOWeekString([date])`

`getUTCWeekNumber([date])`

`new ISOInterval(source[, enforceUTC])`

`interval.type`

`interval.parse()`

`interval.getExpireAt([compareDate[, startDate[, enforceUTC]]])`

`interval.getStartAt([compareDate[, endDate[, enforceUTC]]])`

`interval.toJSON()`

`new ISODate(source[, options])`

`date.parse()`

`date.parsePartialDate(Y, M, D, W)`

`date.toDate([enforceUTC])`

`date.toJSON()`

`new ISODuration(source[, offset])`

`duration.parse()`

`duration.getExpireAt([startDate[, repetition]])`

`duration.getStartAt([endDate[, repetition]])`

`duration.toMilliseconds([startDate[, repetition]])`

`duration.untilMilliseconds([endDate[, repetition]])`