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Non-negative

nonNegative validates that a number is greater than or equal to zero.

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

Signature

Through the API:

.nonNegative()

And internally:

export const nonNegative: 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.not.non-negative Number is less than zero

Design rationale

  • Provides a strict, predictable non-negative number validation.
  • Accepts zero and positive values.
  • 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

nonNegative 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 less than zero, emits number.not.non-negative.
  • If the value is zero or positive → returns an empty result set.

Examples

Valid non-negative number

await nonNegative(5, "$");
// → []

Valid zero

await nonNegative(0, "$");
// → []

Negative number

await nonNegative(-5, "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "number.not.non-negative",
//       path: "$",
//       ...
//     }
//   ]

Non-number value

await nonNegative("5", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "type.not.valid",
//       path: "$",
//       ...
//     }
//   ]