Make a single property optional in TypeScript

For a plug and play solution, consider using the brilliant utility-types package:

npm i utility-types --save

Then simply make use of Optional<T, K>:

import { Optional } from 'utility-types';

type Person = {
  name: string;
  hometown: string;
  nickname: string;
}

type PersonWithOptionalNickname = Optional<Person, 'nickname'>;

// Expect:
//
// type PersonWithOptionalNickname {
//   name: string;
//   hometown: string;
//   nickname?: string;
// }

You can also do something like this, partial only some of the keys.

type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>
type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>

interface Person {
  name: string;
  hometown: string;
  nickname: string;
}

type MakePersonInput = PartialBy<Person, 'nickname'>

Here is my Typescript 3.5+ Optional utility type

type Optional<T, K extends keyof T> = Pick<Partial<T>, K> & Omit<T, K>;

// and your use case
type MakePersonInput = Optional<Person, 'nickname'>

// and if you wanted to make the hometown optional as well
type MakePersonInput = Optional<Person, 'hometown' | 'nickname'>