Maybe Monad로 null 체크 체이닝

type Maybe<T> = T | null

const Maybe = {
  of: <T>(value: T): Maybe<T> => (value != null ? value : null),
  map: <T, U>(m: Maybe<T>, fn: (v: T) => U): Maybe<U> =>
    m != null ? Maybe.of(fn(m)) : null,
}

// 사용 예: DOM 요소 찾아서 스크롤
Maybe.of(scrollElement.current)
  .map((root) => root.querySelector(`#${id}`))
  .map((target) => target.getClientRects()[0])
  .map((rect) => {
    root.scrollLeft = rect.left
  })

Generator로 early return 패턴도 가능

function* handleScroll(id) {
  const root = scrollElement.current
  if (!root) return
  const target = root.querySelector(`#${id}`)
  if (!target) return
  yield target.getClientRects()[0]?.left ?? 0
}