StrictExtract

Since 1.0.0

Strictly extract matching types.

Signature

type StrictExtract<T, U extends T> = T extends U ? T : never

Parameters

Parameter	Description
T	The source type
U	The type to extract (must be a subtype of T)

Description

Similar to TypeScript's built-in Extract, but requires U to be a subtype of T, providing stricter type checking.

Examples

Basic Usage

import type { StrictExtract } from 'uni-types'

type Status = 'pending' | 'active' | 'inactive' | 'deleted'

type ActiveStatus = StrictExtract<Status, 'active' | 'inactive'>
// 'active' | 'inactive'

With Union Types

type Event = {
  type: 'click'
  x: number
  y: number
} | {
  type: 'scroll'
  scrollTop: number
} | {
  type: 'keypress'
  key: string
}

type ClickEvent = StrictExtract<Event, { type: 'click' }>
// { type: 'click'; x: number; y: number }

Related

• StrictExclude - Strictly exclude types
• Extract - TypeScript built-in Extract