# TypeScript's keyof and Mapped Types

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typescript

The keyof operator and mapped types in TypeScript allow for advanced type manipulation. Here’s an example:

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


type UserKeys = keyof User // 'id' | 'name' | 'email'


type ReadonlyUser = {
  [K in keyof User]: Readonly<User[K]>
}


const user: ReadonlyUser = {
  id: 1,
  name: 'John',
  email: 'john@example.com',
}


// user.id = 2; // Error: Cannot assign to 'id' because it is a read-only property.

These features make TypeScript a powerful tool for creating robust and type-safe applications.

Exploring keyof and Mapped Types
echo "Using keyof and mapped types in TypeScript"
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