GuardedType

Since 1.2.0

Extract the guarded type from a type guard function.

Signature

type GuardedType<G> = G extends (value: unknown) => value is infer T ? T : never

Parameters

Parameter	Description
G	The type guard function

Examples

Basic Usage

import type { GuardedType } from 'uni-types'

const isNumber = (value: unknown): value is number => typeof value === 'number'

type Num = GuardedType<typeof isNumber>  // number

With Complex Guards

interface User {
  id: string
  name: string
}

const isUser = (value: unknown): value is User => {
  // guard implementation
}

type UserType = GuardedType<typeof isUser>  // User

Extracting from Array

const guards = [isString, isNumber, isBoolean]
type Types = GuardedType<typeof guards[number]>  // string | number | boolean

Related

• RuntimeGuard - Define type guard function