Strict Mode 와 useEffect의 cleanUp 함수 사례

클린업함수 만드는 방법

 https://ko.react.dev/learn/synchronizing-with-effects#how-to-handle-the-effect-firing-twice-in-development

 

순수함수를 유지하는 방법

 https://ko.react.dev/learn/keeping-components-pure

 

왜 ref는 의존성 배열에서 생략해도 되나요?

 https://ko.react.dev/learn/synchronizing-with-effects#why-was-the-ref-omitted-from-the-dependency-array

 

다시 호출해도 문제 없으면 그냥 둬라
Dialog modal open 처럼 두번 호출하면 에러나는경우 close 를 달아줘야함
https://ko.react.dev/learn/synchronizing-with-effects#controlling-non-react-widgets

 

https://ko.react.dev/learn/synchronizing-with-effects#controlling-non-react-widgets

 

이벤트를 구독하면 해제해야한다
https://ko.react.dev/learn/synchronizing-with-effects#subscribing-to-events

 

애니메이션처리를 위해 CSS 스타일이나 클래스를 변경한 경우
https://ko.react.dev/learn/synchronizing-with-effects#triggering-animations

 

데이터 페칭 
만약 Effect가 어떤 데이터를 가져온다면, 클린업 함수에서는 fetch를 중단하거나 결과를 무시해야 합니다.