JS Practice — Built-in Objects

Utility Types — typeof + ReturnType<T>

📖 Usage Example

function makeUser() { return { name: 'Alice', age: 30 } }
type User = ReturnType<typeof makeUser>
// User = { name: string; age: number }

ReturnType<T> extracts the return type of a function type, enabling DRY type inference.

Utility Types: ReturnType<T>

ReturnType<T> extracts the return type of a function type T.

Challenge: Implement getValues<T extends object>(obj: T): T[keyof T][] returning all values of an object.

getValues({ a: 1, b: 2, c: 3 })  // → [1, 2, 3]

💡 Hints (1)