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Is far future

isFarFuture validates that a Date instance represents a year strictly greater than 2100.

It performs a strict type check ensuring the value is a valid Date instance, then validates that the year is after 2100. If the value is not a Date, is invalid, or represents a year 2100 or earlier, the rule emits a single validation event. Otherwise, it produces no validation output.

Signature

Through the API:

.isFarFuture()

And internally:

export const isFarFuture: ValidationRule
(value: unknown, path: FieldPath) => Promise<ReadonlyArray<JaneEvent>>

Events

Event code Description
date.not.date Value is not a Date instance
date.is.invalid Date instance represents an invalid date
date.is.far-future Date represents year 2100 or earlier

Design rationale

  • Provides a strict, predictable far-future date validation.
  • First ensures the value is a valid Date instance.
  • Then validates the year is strictly greater than 2100.
  • Useful for preventing data entry errors or enforcing long-term future dates.
  • Never coerces or normalizes — validation is explicit and opt-in.
  • Emits exactly one event per failure for clarity and composability.
  • Async-compatible and returns a readonly array of JaneEvent objects.

Invoke

isFarFuture runs only when explicitly included in a boundary or pipeline. It does not run automatically.

The rule activates when:

  • The value is any JavaScript value.
  • If the value is not a Date instance, emits date.not.date.
  • If the value is a Date but invalid, emits date.is.invalid.
  • If the value is a valid Date but year ≤ 2100, emits date.is.far-future.
  • If the value is a valid Date after 2100 → returns an empty result set.

Examples

Far future date

await isFarFuture(new Date("2200-01-01"), "$");
// → []

Recent date

await isFarFuture(new Date("2023-01-01"), "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "date.is.far-future",
//       path: "$",
//       ...
//     }
//   ]

Non-Date value

await isFarFuture("2200-01-01", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "date.not.date",
//       path: "$",
//       ...
//     }
//   ]