# ValidatorFn

# Type Alias: ValidatorFn\<TParameter, TReturn\>

```ts
type ValidatorFn<TParameter, TReturn> = (...args) => TReturn | Promise<TReturn>;
```

Defined in: [validation.public.ts:429](https://github.com/TanStack/form/blob/main/packages/form-core/src/validation.public.ts#L429)

## Type Parameters

### TParameter

`TParameter`

### TReturn

`TReturn`

## Parameters

### args

...`TParameter`[]

## Returns

`TReturn` \| `Promise`\<`TReturn`\>