Interfaces & Object Types

Describing object shapes

TypeScript lets you describe the exact shape an object must have using an interface or a type alias.

Interface

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

const user: User = { name: "Alice", age: 30 };

An interface is like a contract. If you forget a field or use the wrong type TypeScript will tell you immediately.

Optional fields

Add ? to mark a field as optional:

interface Product {
  id: number;
  name: string;
  description?: string; // optional
}

Type aliases

type does the same thing and is often interchangeable with interface:

type Point = {
  x: number;
  y: number;
};

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Your task

Define and export a User interface with:

• name: string
• age: number
• email?: string (optional)

Then create and export a user object that matches it, with at least name and age filled in.