trofivan

type First<T extends readonly unknown[]> = T extends readonly [infer F, ...unknown[]] ? F : never
type Last<T extends readonly unknown[]> = T extends readonly [...unknown[], infer L] ? L : never
type Rest<T extends readonly unknown[]> = T extends readonly [unknown, ...infer R] ? R : never

const arr = [1, '2', Symbol(3), undefined, null] as const

type F = First<typeof arr>  // 1
type L = Last<typeof arr>   // null
type R = Rest<typeof arr>   // ['2', symbol, undefined, null]

trofivan

const getValue = <T, K1 extends keyof T, K2 extends keyof T[K1]>(obj: T, key1: K1, key2?: K2) =>
  key2 ? obj[key1][key2] : obj[key1]

const response = {
  type: 'get',
  result: {
    status: 200
  },
  article: {
    id: 1,