Built-in TypeScript utility types Partial, Required, Readonly, Pick, Omit

Utility types overview

TypeScript ships built-in utility types that transform existing types without rewriting them:

interface User {
  id: number;
  name: string;
  email: string;
  password: string;
}

type PartialUser  = Partial;          // all fields optional
type RequiredUser = Required>; // all fields required
type ReadonlyUser = Readonly;          // all fields readonly
type PublicUser   = Omit; // remove password
type Credentials  = Pick; // keep only these

Real-world patterns

// Update endpoint: only send changed fields
function updateUser(id: number, changes: Partial>) {
  // changes has optional name, email, password — no id
}

// Create endpoint: no id (auto-generated)
type CreateUserDTO = Omit;
function createUser(dto: CreateUserDTO): User {
  return { id: Date.now(), ...dto };
}

Composing utility types is idiomatic TypeScript. You rarely need to manually rewrite types when these tools cover the common transformations.