Mapped types

⬅️ Execute Program Advanced TypeScript

Mapped types

• We can think of Partial as “mapping” the object type’s properties into a new set of properties

type User = {
  email: string
};
 
type UserAggregate = {
	// mapping over the user properties
  [K in keyof User]: Array<string>
};
 
const userAggregate: UserAggregate = {
  email: ['amir@example.com'],
};
userAggregate.email;
 
 
// with two properties, respecting the type
type User = {
  email: string
  age: number
};
 
type UserAggregate = {
  [K in keyof User]: Array<User[K]>
};
 
const userAggregate: UserAggregate = {
  email: ['amir@example.com'],
  age: [36],
};
userAggregate;