Pattern

Croner is fully compliant with the Open Cron Pattern Specification (OCPS) versions 1.0 through 1.4. The expressions are based on Vixie Cron with powerful extensions:

// ┌──────────────── (optional) second (0 - 59)
// │ ┌────────────── minute (0 - 59)
// │ │ ┌──────────── hour (0 - 23)
// │ │ │ ┌────────── day of month (1 - 31)
// │ │ │ │ ┌──────── month (1 - 12, JAN-DEC)
// │ │ │ │ │ ┌────── day of week (0 - 6, SUN-Mon) 
// │ │ │ │ │ │       (0 to 6 are Sunday to Saturday; 7 is Sunday, the same as 0)
// │ │ │ │ │ │
// * * * * * *

• OCPS 1.2: Optional second and year fields for enhanced precision:

  • 6-field format: SECOND MINUTE HOUR DAY-OF-MONTH MONTH DAY-OF-WEEK
  • 7-field format: SECOND MINUTE HOUR DAY-OF-MONTH MONTH DAY-OF-WEEK YEAR
  • Supported year range: 1-9999

• OCPS 1.3: Advanced calendar modifiers:

  • L: Last day of month or last occurrence of a weekday. L in day-of-month = last day of month; 5#L or FRI#L = last Friday of the month.
  • W: Nearest weekday. 15W triggers on the weekday closest to the 15th (moves to Friday if 15th is Saturday, Monday if 15th is Sunday). Won't cross month boundaries.
  • #: Nth occurrence of a weekday. 5#2 = second Friday; MON#1 = first Monday of the month.

• OCPS 1.4: Enhanced logical control:

  • +: Explicit AND logic modifier. Prefix the day-of-week field with + to require both day-of-month AND day-of-week to match. Example: 0 12 1 * +MON only triggers when the 1st is also a Monday.
  • ?: Wildcard alias (behaves identically to *). Non-portable: Its use is discouraged in patterns intended for cross-system use. Supported in all fields for compatibility, but primarily meaningful in day-of-month and day-of-week fields.
  • Proper DST handling: Jobs scheduled during DST gaps are skipped; jobs in DST overlaps run once at first occurrence.

• Croner allows you to pass a JavaScript Date object or an ISO 8601 formatted string as a pattern. The scheduled function will trigger at the specified date/time and only once. If you use a timezone different from the local timezone, you should pass the ISO 8601 local time in the target location and specify the timezone using the options (2nd parameter).

• By default, Croner uses OR logic for day-of-month and day-of-week (OCPS 1.0 compliant). Example: 0 20 1 * MON triggers on the 1st of the month OR on Mondays. Use the + modifier (0 20 1 * +MON) or { legacyMode: false } option for AND logic. For more information, see issue #53.

Weekday and month names are case-insensitive. Both MON and mon work. When using L in the Day of Week field with a range, it affects all specified weekdays. For example, 5-6#L means the last Friday and Saturday in the month. The # character specifies the "nth" weekday of the month. For example, 5#2 = second Friday, MON#1 = first Monday. The W character operates within the current month and won't cross month boundaries. If the 1st is a Saturday, 1W matches Monday the 3rd. The + modifier (OCPS 1.4) enforces AND logic: 0 12 1 * +MON only runs when the 1st is also a Monday.

OCPS 1.1: Predefined schedule nicknames are supported: