API reference / @evolu/common / Type / undefinedOr

Function: undefinedOr()

function undefinedOr<T>(
  type,
): UnionType<
  [
    Type<
      "Undefined",
      undefined,
      undefined,
      UndefinedError,
      undefined,
      UndefinedError
    >,
    T,
  ]
>;

Defined in: packages/common/src/Type.ts:3172

union(undefined, T) Type.

Example

const UndefinedOrString = undefinedOr(String);
UndefinedOrString.from("world"); // ok("world")
UndefinedOrString.from(undefined); // ok()
UndefinedOrString.from(42); // err(...)

Type Parameters

Type Parameter
`T` extends `AnyType`

Parameters

Parameter	Type
`type`	`T`

Returns

UnionType<[Type<"Undefined", undefined, undefined, UndefinedError, undefined, UndefinedError>, T]>