Types & Interfaces

Types and Interfaces

TypeScript lets you describe the shape of objects with type aliases and interface declarations.

type alias

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

interface

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

Both are nearly identical. type is slightly more flexible (union types, tuples), interface is preferred for object shapes by many teams.

Using your types

function formatUser(user: User): string {
  return `${user.name} (${user.age})`;
}

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Your task

Define and export a type named Point with:

• x: number
• y: number

Then export a function named distance that takes two Point values and returns the Euclidean distance between them as a number.

export type Point = { ... };

export function distance(a: Point, b: Point): number {
  // hint: Math.sqrt((b.x - a.x) ** 2 + (b.y - a.y) ** 2)
}