TypeCheckCallback type

Callback for deciding if a value matches a given type T.

Signature:

type TypeCheckCallback<T = defined> = (value: T) => boolean | string | void;

Remarks

Returning a boolean of true means that the value passes the check, and is of type T. Alternatively, not returning anything (void) will also count as a pass.

On the other hand, a boolean of false means that the value did NOT pass the check, and an error will be thrown.

You can also return a string, in which case it will also be treated as a failure- but the string you provide will be propogated as a reason in the failure.

Example

const isNumber: TypeCheckCallback = (value) => {
  return typeOf(value) === "number";
}