IsEqual

Since 1.0.0

Check if two types are exactly equal.

Signature

type IsEqual<X, Y> = 
  (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2
    ? true
    : false

Parameters

Parameter	Description
X	First type to compare
Y	Second type to compare

Returns

Returns true if X and Y are exactly the same type, false otherwise.

Examples

Basic Usage

import type { IsEqual } from 'uni-types'

type Check1 = IsEqual<string, string> // true
type Check2 = IsEqual<number, number> // true
type Check3 = IsEqual<'hello', 'hello'> // true

Object Types

type Check4 = IsEqual<{ a: string }, { a: string }> // true
type Check5 = IsEqual<{ a: string }, { a: number }> // false
type Check6 = IsEqual<{ a: string }, { b: string }> // false

Different Types

type Check7 = IsEqual<string, number> // false
type Check8 = IsEqual<string | number, number | string> // true

Special Types

type Check9 = IsEqual<any, unknown> // false
type Check10 = IsEqual<any, any> // true
type Check11 = IsEqual<never, never> // true

Usage in Conditional Types

import type { IsEqual } from 'uni-types'

type Expect<T extends true> = T

// Type-level assertions
type Test1 = Expect<IsEqual<string, string>>
type Test2 = Expect<IsEqual<1, 1>>

// This would cause a type error:
// type Test3 = Expect<IsEqual<string, number>>

Related

• IsAny - Check if type is any
• IsNever - Check if type is never
• IsUnknown - Check if type is unknown