Terms

Use parseRuleExpression to create a rule from a short text expression:

import { parseRuleExpression } from "@kensio/quando";

parseRuleExpression("mon-fri 09:00-17:00 @Europe/London");

Separate terms with spaces. Each term adds a condition, and every condition must match. Term order has no effect. The parser returns the same rule objects as the builders, which also support more complex combinations.

Combine conditions and alternatives

Spaces combine conditions with AND. Commas within a term combine alternatives with OR:

parseRuleExpression("mon-fri 09:00-17:00");
// all(daysOfWeek(monday…friday), timeOfDayRange("09:00", "17:00"))

parseRuleExpression("sat,sun");
// daysOfWeek("saturday", "sunday")

09:00-12:00,14:00-17:00 covers the morning or the afternoon, with a lunch break between them. 09:00-12:00 14:00-17:00 requires both ranges to match at once and therefore covers no time.

Combine separate expressions in a schedule

Use separate schedule calls for alternatives with different conditions. For example, weekday hours and Saturday hours need separate expressions:

const shop = schedule({ zone: "Europe/London" })
  .open("mon-fri 09:00-17:00")
  .open("sat 10:00-14:00")
  .closed("2026-12-25");

const saturdayTea = Temporal.ZonedDateTime.from(
  "2026-03-14T16:00[Europe/London]",
);

shop.isOpen(saturdayTea); // false
shop.nextOpenInterval(saturdayTea)?.start?.toString();
// 2026-03-16T09:00:00+00:00[Europe/London]

Schedule, rota, and tally methods accept these expressions wherever they accept a rule. This includes open, closed, and setHours.

Supported terms

The parser recognises weekday names, dates, time ranges, and the other forms listed below:

Written	Means
weekdays	Monday to Friday
weekends	Saturday and Sunday
mon, monday	one weekday, in full or in three letters
mon-fri	a run of days, wrapping, so fri-mon works
sat,sun	either day
09:00-17:00	a window in the day, and 9:00-17:00 too
jan-mar, june	months by name
M01, M05L	a month by code, for a non-Gregorian calendar
2026-12-25	one date, and a comma gives several
2026-07-01..2026-08-31	a stretch, open at either end if one is left off
@Europe/London	the clock the whole line is read on

Use a prefix when a value could have several meanings. For example, day:15 selects the fifteenth day of the month:

Written	Means
day:1,15,-1	days of the month, counting from either end
month:3,6	months by number, for a line a program wrote
nth:-1,fri	the last Friday of the month
every:2w@2026-01-05	every second week, in phase with that date
cal:hebrew	the calendar the whole line counts on
except:2026-12-25	whatever the term after it covers, taken away
holidays:gb	a custom rule, and the options it is given

The period units for every are d (days), w (weeks), mo (months), and y (years). The ambiguous abbreviation m is rejected.

every requires an explicit anchor date after @. The anchor determines which periods match, independently of when the expression is parsed.

Invalid expressions

Names are case-insensitive and accept their supported full or abbreviated forms. Numeric terms accept leading zeros. An unrecognised term causes the whole expression to fail:

parseRuleExpression("weekdays excpet:2026-12-25");
// RangeError: Term 2: "excpet:2026-12-25" is not a term.
//   Did you mean "except:"?

parseRuleExpression("weekdys 09:00-17:00");
// RangeError: Term 1: cannot read "weekdys". Did you mean "weekdays"?

The error identifies the term and may suggest a correction. The parser never silently discards an invalid condition.

Limits

Expressions support one flat set of conditions. Use the builders or separate schedule layers for nested combinations such as any(all(a, b), all(c, d)). except: excludes a single term.

Quando cannot convert a rule back to this text syntax. Store complete rule definitions as JSON. toCron and toRRule export the subsets those formats support.