TypeScript utility types: omit and pick

As is in the name, at the heart of everything TypeScript offers, are types. As you pass around data, having a predictable structure helps not only reduce run-time errors but also improves developer productivity as you have IntelliSense support in your favourite IDE.

However, sometimes you only want a subset of data from a larger object, which is where TypeScript's utility types come in:

• Omit

• Pick

These let you create new types based on an existing type, but filtering in/out specific properties:

type User = {
  username: string;
  firstName: string;
  lastName: string;
  emailAddress: string;
  avatarUrl: string;
  address: {
    addressLine1: string;
    addressLine2: string;
  };
  createdAt: Date;
}

// Provides only username and avatarUrl properties
type MessageBoardUser = Pick<User, "username" | "avatarUrl">

// Provides firstName, lastName, emailAddress and address properties
type ShippingUser = Omit<User, "username" | "avatarUrl" | "createdAt">