feat: Temporal dates and times#4759
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kerams
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Jul 10, 2026
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| declare global { | ||
| namespace Temporal { | ||
| class PlainDate { | ||
| constructor(isoYear: number, isoMonth: number, isoDay: number); | ||
| static compare(one: PlainDate, two: PlainDate): number; | ||
| readonly year: number; | ||
| readonly month: number; | ||
| readonly day: number; | ||
| readonly dayOfWeek: number; | ||
| readonly dayOfYear: number; | ||
| add(duration: { years?: number, months?: number, days?: number }): PlainDate; | ||
| until(other: PlainDate): Duration; | ||
| equals(other: PlainDate): boolean; | ||
| } | ||
| class Duration { | ||
| readonly days: number; | ||
| } | ||
| namespace Now { | ||
| function plainDateISO(): PlainDate; | ||
| } | ||
| } | ||
| } | ||
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| export type DateOnly = Temporal.PlainDate; | ||
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| export const PlainDate = Temporal.PlainDate; | ||
| export type PlainDate = Temporal.PlainDate; |
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This will go (likewise in the other file) once we upgrade to Typescript 6 or 7.
kerams
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Jul 10, 2026
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| export function parse(str: string): DateOnly { | ||
| function fail(): DateOnly { | ||
| throw new Exception(`String '${str}' was not recognized as a valid DateOnly.`); | ||
| } | ||
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| // Allowed separators: . , / - | ||
| // TODO whitespace alone as the separator | ||
| // | ||
| // Whitespace around separators | ||
| // | ||
| // Allowed format types: | ||
| // yyyy/mm/dd | ||
| // mm/dd/yyyy | ||
| // mm/dd | ||
| // mm/yyyy | ||
| // yyyy/mm | ||
| const r = /^\s*(\d{1,4})(?:\s*[.,-\/]\s*(\d{1,2}))?\s*[.,-\/]\s*(\d{1,4})\s*$/.exec(str); | ||
| if (r != null) { | ||
| let y = 0; | ||
| let m = 0; | ||
| let d = 1; | ||
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| if (r[2] == null) { | ||
| if (r[1].length < 3) { | ||
| if (r[3].length < 3) { | ||
| // 12/30 = December 30, {CurrentYear} | ||
| y = Temporal.Now.plainDateISO().year; | ||
| m = +r[1]; | ||
| d = +r[3]; | ||
| } else { | ||
| // 12/2000 = December 1, 2000 | ||
| m = +r[1]; | ||
| y = +r[3]; | ||
| } | ||
| } else { | ||
| if (r[3].length > 2) | ||
| fail(); | ||
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| // 2000/12 = December 1, 2000 | ||
| y = +r[1]; | ||
| m = +r[3]; | ||
| } | ||
| } else { | ||
| // 2000/1/30 or 1/30/2000 | ||
| const yearFirst = r[1].length > 2; | ||
| const yTmp = r[yearFirst ? 1 : 3]; | ||
| y = +yTmp; | ||
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| // year 0-29 is 2000-2029, 30-99 is 1930-1999 | ||
| if (yTmp.length < 3) | ||
| y += y >= 30 ? 1900 : 2000; | ||
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| m = +r[yearFirst ? 2 : 1]; | ||
| d = +r[yearFirst ? 3 : 2]; | ||
| } | ||
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| if (y > 0) { | ||
| try { | ||
| return new Temporal.PlainDate(y, m, d); | ||
| } catch { | ||
| return fail(); | ||
| } | ||
| } | ||
| } | ||
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| return fail(); | ||
| } |
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This parse (likewise in the other file) is only necessary if we want to closely follow .NET's parse behaviour. We could decide to remove it and instead delegate to from, which should still be close enough and acceptable in the vast majority of cases.
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Implements #4751.
Opt-in with
--test:js-temporal, which definesFABLE_COMPILER_JAVASCRIPT_TEMPORAL.DateOnlyasPlainDateTimeOnlyasPlainTimeDateTimeasPlainDateTimeextended with kind metadataDateTimeOffsetasZonedDateTimewith an offset-based time zone rather than IANATimeSpanasDurationAll these types have nanosecond precision, whereas the old representation truncates everything below milliseconds (partly due to
Date), which is something that bit me in the past. However, the precision in .NET is a tick (100ns), so the current implementation is truncating nanosecond values on construction and value access.