/** * [α] T 型から undefined 不可キーの union を抽出 */ type RequiredKeys<T> = { [K in keyof T]-?: Record<any, unknown> extends Pick<T, K> ? never : K; }[keyof T]; /** * [β] α を利用し, Passed 型から Req 型の条件を満たさないものだけを抽出 */ type MissingKeys<Req, Passed extends Partial<Req>> = { [K in keyof Pick< Req, RequiredKeys<Req> >]: Passed[K] extends Req[K] ? never : K; }[keyof Pick<Req, RequiredKeys<Req>>]; /** * [γ] β を利用し
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