IsUnknown

Since 1.0.0

Check if a type is unknown.

Signature

type IsUnknown<T> = IsEqual<T, unknown> extends true
  ? IsAny<T> extends true
    ? false
    : true
  : false

Parameters

Parameter	Description
T	The type to check

Returns

Returns true if T is unknown, false otherwise.

Examples

Basic Usage

import type { IsUnknown } from 'uni-types'

type Check1 = IsUnknown<unknown> // true

Non-Unknown Types

type Check2 = IsUnknown<string> // false
type Check3 = IsUnknown<any> // false (any is not unknown)
type Check4 = IsUnknown<never> // false
type Check5 = IsUnknown<{}> // false

Usage in Conditional Types

import type { IsUnknown } from 'uni-types'

// Handle unknown type specially
type HandleUnknown<T> = IsUnknown<T> extends true 
  ? 'was unknown' 
  : T

type Test1 = HandleUnknown<string> // string
type Test2 = HandleUnknown<unknown> // 'was unknown'

Related

• IsAny - Check if type is any
• IsNever - Check if type is never
• IsEqual - Check if types are equal