TypeScript: Utility Types

TypeScript provides several utility types to facilitate common type transformations. Here are some of them with the examples ✨

Partial

lets us make all required fields optional.

type User = {
  name: string;
  email: string;
  age: number;
  gender: string;
};

type PartialUser = Partial<User>;

const emptyUser: PartialUser = {};
const partialUser: PartialUser = {
  name: "John Doe"
};

Required

lets us make all optional fields required.

type User = {
  name: string;
  email: string;
  age?: number;
  gender?: string;
};

type RequiredUser = Required<User>;

const user: RequiredUser = {
  name: "Jane Doe",
  email: "jane@doe.com",
  age: 29,
  gender: "female"
};

Pick

lets us pick some fields to create a new type based on an existing one.

type Article = {
  title: string;
  description: string;
  url: string;
  image: string;
}

type ArticlePreview = Pick<Article, "title" | "description">;

const articlePreview: ArticlePreview = {
  name: "Visiting Ireland? Here’s what the locals love",
  description: "Looking for the best castles, golf courses, or restaurants?"
}; 

Omit

lets us exclude some properties and create a new type based on an existing one.

type Todo = {
  title: string;
  description: string;
  completed: boolean;
  createdAt: number;
}

type TodoPreview = Omit<Todo, "description" | "createdAt">;

const todo: TodoPreview = {
  title: "Morning 🧘🏻‍♀",
  completed: true
};