Type Alias SetReadonly<BaseType, Keys>

SetReadonly: BaseType extends unknown
? Simplify<Except<BaseType, Keys> & Readonly<Pick<BaseType, Keys>>>
: never

Create a type that makes the given keys readonly. The remaining keys are kept as is.

Use-case: You want to define a single model where the only thing that changes is whether or not some of the keys are readonly.

Type Parameters

BaseType
Keys extends keyof BaseType

Example

import type {SetReadonly} from 'type-fest';

type Foo = {
	a: number;
	readonly b: string;
	c: boolean;
}

type SomeReadonly = SetReadonly<Foo, 'b' | 'c'>;
// type SomeReadonly = {
// 	a: number;
// 	readonly b: string; // Was already readonly and still is.
// 	readonly c: boolean; // Is now readonly.
// }