Quiz · 3 questions

🧰 Utility Types — The Built-in Standard Library of Types

Partial, Required, Pick, Omit, Record, ReturnType, Parameters, Awaited, NonNullable

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01What does Partial<User> produce?

Hint

Partial is implemented as type Partial<T> = { [K in keyof T]?: T[K] } — a mapped type with ?.

02What's the difference between Pick<T, K> and Omit<T, K>?

Hint

Pick<User, keyof User> equals User. Omit<User, never> equals User. The extremes give you back the original.

03What does Awaited<Promise<Promise<string>>> give you?

Hint

Try await Promise.resolve(Promise.resolve('hi')) at runtime — JavaScript also unwraps both levels.

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