Item 1-7 Study Summary

스터디 안건: keyof와 Union(|), Intersection(&)을 이용한 아이큐 퀴즈 (?)

interface Person{ name: string; }

interface Lifespan{ birth: Date; death? : Date; }

type K = keyof (Person | Lifespan); //타입이 never

interface Person {
  name: string
}

interface Lifespan {
  birth: Date
  death?: Date
}

type Intersection = keyof (Person & Lifespan) // name, birth, death
type 분배Union = keyof Person | keyof Lifespan // name, birth, death

type Union = keyof (Person | Lifespan) // 타입이 never
type 분배Intersection = keyof Person & keyof Lifespan // never

const k: Intersection = 'name'
const i: Union = 'name'
const m: 분배Intersection = 'name'
const j: 분배Union = 'name'

분배법칙이 NOT처럼 적용된다.

• keyof (A & B) == keyof A | keyf B == A와 B의 키의 합집합

• keyof (A | B) == keyof A & keyof B == never