Type Utilities

Built-in utility types

TypeScript ships with utility types that let you create new types by transforming existing ones. You never need to re-write common patterns.

Partial<T>

Makes every property of T optional — great for update payloads:

interface User {
  name: string;
  age: number;
  email: string;
}

type UserUpdate = Partial<User>;
// { name?: string; age?: number; email?: string }

Required<T>

The opposite — makes every property required:

type RequiredUser = Required<UserUpdate>;
// { name: string; age: number; email: string }

Pick<T, Keys>

Select a subset of properties:

type UserPreview = Pick<User, "name" | "email">;
// { name: string; email: string }

Omit<T, Keys>

Drop specific properties:

type PublicUser = Omit<User, "email">;
// { name: string; age: number }

Readonly<T>

Prevents any property from being reassigned:

const config: Readonly<User> = { name: "Alice", age: 30, email: "a@b.com" };
config.name = "Bob"; // ❌ Error

Record<Keys, Value>

Create an object type with specific keys and a uniform value type:

type ScoreMap = Record<string, number>;
const scores: ScoreMap = { alice: 95, bob: 87 };

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Your task

Given this interface:

interface Product {
  id: number;
  name: string;
  price: number;
  description: string;
}

1. Export ProductPreview — a Pick of id and name only
2. Export ProductUpdate — a Partial of Product
3. Export ProductWithoutDesc — an Omit of description
4. Export a function createPreview(p: Product): ProductPreview that returns just the id and name