ReadonlyKeys

Since 1.0.0

Get readonly property keys.

Signature

type ReadonlyKeys<T> = {
  [K in keyof T]-?: IfEquals<
    { [Q in K]: T[K] },
    { -readonly [Q in K]: T[K] },
    never,
    K
  >
}[keyof T]

Parameters

Parameter	Description
T	The object type

Description

Extracts all readonly property keys from an object type.

Examples

Basic Usage

import type { ReadonlyKeys } from 'uni-types'

interface User {
  id: number
  name: string
  readonly email: string
  readonly createdAt: Date
}

type Readonly = ReadonlyKeys<User>
// 'email' | 'createdAt'

All Writable

interface WritableUser {
  id: number
  name: string
}

type NoReadonly = ReadonlyKeys<WritableUser> // never

Related

• WritableKeys - Get writable property keys
• RequiredKeys - Get required property keys
• OptionalKeys - Get optional property keys