Reference · Dates

date.at

date.at(str, str | null=, str | map | null=, map | null=) -> str

What it does

The instant a local time names: a date, a time of day "HH:MM" or "HH:MM:SS", and a time zone, as a date-time written at that zone's offset. date.at("2026-10-27", "17:00", "America/New_York") is "2026-10-27T17:00:00-04:00", five in the afternoon in New York, with the offset of that day. The time left out (or null) is midnight; the zone left out is UTC. It takes a date, not a date-time.

Examples

print(date.at("2026-10-27", "17:00", "America/New_York"))print(date.at("2026-10-27", "09:15:30", "Asia/Kolkata"), date.at("2026-10-27", "17:00"))print(date.at("2026-10-27"), date.at("2026-10-27", null, "Europe/Paris"))

2026-10-27T17:00:00-04:002026-10-27T09:15:30+05:30 2026-10-27T17:00:00Z2026-10-27T00:00:00Z 2026-10-27T00:00:00+01:00

Edge cases

• A time that the clocks skip when they go forward is moved on by the gap: 02:30 on the night Paris springs forward is 03:30. A time that happens twice when they go back is the first, the one still on summer time. Options last say otherwise: { repeated: "later" } takes the second of the two, and { skipped: "earlier" } moves a skipped time back, or { skipped: "error" } gives an error value.
• The date and the time may be one text, as <input type="datetime-local"> gives them: date.at("2026-10-27T14:30", "America/New_York"), the options third.
• The result is in local form; date.to_zone it for UTC, or date.ms for a number.
• The zone can be a fixed offset, written +05:30, +0530 or +05; a name is the IANA database's in any case, the same on the server and in the browser (see date.valid_zone).

print(date.at("2026-03-29", "02:30", "Europe/Paris"), date.at("2026-10-25", "02:30", "Europe/Paris"))print(date.at("2026-03-08", "02:30", "America/New_York"), date.at("2026-11-01", "01:30", "America/New_York"))print(date.at("2026-10-27", "17:00", "Europe/Paris") | date.to_zone)print(date.at("2026-10-27", "23:59:59", "-10:00"))print(date.at("2026-11-01", "01:30", "America/New_York", { repeated: "later" }), date.at("2026-03-08", "02:30", "America/New_York", { skipped: "earlier" }))print(date.at("2026-10-27T14:30", "America/New_York"), date.at("2026-03-08T02:30", "America/New_York", { skipped: "error" }))

2026-03-29T03:30:00+02:00 2026-10-25T02:30:00+02:002026-03-08T03:30:00-04:00 2026-11-01T01:30:00-04:002026-10-27T16:00:00Z2026-10-27T23:59:59-10:002026-11-01T01:30:00-05:00 2026-03-08T01:30:00-05:002026-10-27T14:30:00-04:00 err("date.at: 2026-03-08 02:30 is skipped in that zone, as its clocks move forward")

Errors

A date-time or text that is not a date, a time that is not HH:MM or HH:MM:SS with real hours, minutes and seconds, or an unknown zone is a runtime error, not an error value.

print(date.at("2026-10-27", "5pm"))

line 1: `date.at` expects a time (HH:MM or HH:MM:SS) as argument 2, got "5pm"

print(date.at("2026-10-27T10:00:00Z", "17:00"))

line 1: `date.at` expects a date (YYYY-MM-DD) as argument 1, got the date-time "2026-10-27T10:00:00Z" (`date.date_in` gives its date)

Chaining

The date comes first, so a day from a form becomes an instant for storing or comparing:

print("2026-10-27" | date.at("17:00", "America/New_York") | date.date_in("Asia/Tokyo"))print("2026-10-27" | date.at("09:00", "Europe/Lisbon") | date.ms)print(["2026-10-27", "2026-10-28"] | map((d) => date.at(d, "12:00", "+05:30")))

2026-10-281793091600000["2026-10-27T12:00:00+05:30", "2026-10-28T12:00:00+05:30"]

See also

date.to_zone, date.date_in, date.ms, date.from_ms, date.parts

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