Mutable type

Removes readonly from the properties of a type, one level deep: a builder filling an object before handing it out as read-only.

import type { Mutable } from 'utils';

Signature

export type Mutable<T> = { -readonly [K in keyof T]: T[K] };

Parameters

Name	Description
T	The read-only type.

Example

const draft: Mutable<Point> = { x: 0, y: 0 };
draft.x = 10;

Tests

Line coverage: 0 %.

• ✅ removes readonly

Source

src/types/mutable.ts (on GitHub)

Source code

/**
 * Removes `readonly` from the properties of a type, one level deep: a builder filling an object before
 * handing it out as read-only.
 *
 * @template T - The read-only type.
 * @example
 * const draft: Mutable<Point> = { x: 0, y: 0 };
 * draft.x = 10;
 */
export type Mutable<T> = { -readonly [K in keyof T]: T[K] };

Test file

import type { Mutable } from './mutable';

describe('Mutable', () => {
  it('removes readonly', () => {
    expectTypeOf<Mutable<{ readonly x: number }>>().toEqualTypeOf<{ x: number }>();
  });
});

Keywords: mutable, types, type