IsNever

Since 1.0.0

Check if a type is never.

Signature

type IsNever<T> = [T] extends [never] ? true : false

Parameters

Parameter	Description
T	The type to check

Returns

Returns true if T is never, false otherwise.

Examples

Basic Usage

import type { IsNever } from 'uni-types'

type Check1 = IsNever<never> // true

Non-Never Types

type Check2 = IsNever<string> // false
type Check3 = IsNever<undefined> // false
type Check4 = IsNever<null> // false
type Check5 = IsNever<void> // false

Usage in Conditional Types

import type { IsNever } from 'uni-types'

// Handle never type specially
type HandleNever<T> = IsNever<T> extends true 
  ? 'was never' 
  : T

type Test1 = HandleNever<string> // string
type Test2 = HandleNever<never> // 'was never'

Related

• IsAny - Check if type is any
• IsUnknown - Check if type is unknown
• IsEqual - Check if types are equal