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Utils

ValueOf

Extracts the value types from an object (similar to `keyof` but for values).

The ValueOf<T> utility type extracts the union of all value types from a given object type T.

It functions similarly to the built-in keyof operator, but instead of retrieving the keys, it retrieves the distinct types of the values assigned to those keys.

Definition

ValueOf.ts
/**
 * Extracts the value types from an object (similar to `keyof` but for values).
 */
export type ValueOf<T> = T[keyof T];

Example Usage

This is particularly useful when working with configuration constants or enums represented as constant objects (as const), where you need to restrict a variable to only the values defined in the object.

example.ts
import type { ValueOf } from '@riavzon/utils'

const STATUS_CODES = {
  OK: 200,
  CREATED: 201,
  BAD_REQUEST: 400,
  UNAUTHORIZED: 401,
  NOT_FOUND: 404
} as const;

// Extracts: 200 | 201 | 400 | 401 | 404
type StatusCode = ValueOf<typeof STATUS_CODES>;

// Allowed
const validStatus: StatusCode = 200;

// Error: Type '500' is not assignable to type 'StatusCode'.
const invalidStatus: StatusCode = 500; 

function sendResponse(status: StatusCode) {
  // ...
}

StandardResponse

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