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Max

max validates that a number is less than or equal to a specified maximum value.

It enforces strict numeric validation and rejects any non-number value or number above the threshold. If the value is not a number or is too large, the rule emits a single validation event. Otherwise, it produces no validation output.

Signature

Through the API:

.max(maximum: number)

And internally:

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

Events

Event code Description
type.not.valid Value is not structurally a number or is NaN
number.too.high Number exceeds the maximum threshold

Design rationale

  • Provides a strict, predictable numeric maximum validation.
  • Rejects non-number values with a clear structural-type diagnostic.
  • 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

max 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 number or is NaN, emits type.not.valid.
  • If the value is a number but greater than the maximum, emits number.too.high.
  • If the value is a number at or below the maximum → returns an empty result set.

Examples

Valid number at maximum

await max(100)(100, "$");
// → []

Number above maximum

await max(100)(150, "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "number.too.high",
//       path: "$",
//       ...
//     }
//   ]

Non-number value

await max(100)("150", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "type.not.valid",
//       path: "$",
//       ...
//     }
//   ]