typescript 在type中如何过滤可选属性

Question

例如

 type A = {
    name: string
    age?: number
    sex?: number
  }

  type B = FilterOptional<A> // => { name: string }

把所有可选的属性过滤掉，这个FilterOptional应该怎么写

Answer 1

type FilterOptional<T extends {}> = Pick<T, { [K in keyof T]-?: undefined extends T[K] ? never : K }[keyof T]>
type B = FilterOptional<A> // => { name: string }

Answer 2

type FilterOptional<T extends object> = Pick<T, Exclude<{
    [K in keyof T]: T extends Record<K, T[K]>
    ? K
    : never
}[keyof T], undefined>>;