TIl 2020/07/28

const checkAnswer = (index: number) => {
    if (
      state.omrWithAnswers[page] &&
      state.omrWithAnswers[page][quizNumber] &&
      state.omrWithAnswers[page][quizNumber].answersByAdmin &&
      state.omrWithAnswers[page][quizNumber].answersByUser &&
      state.omrWithAnswers[page][quizNumber].answersByUser[0] &&
      state.omrWithAnswers[page][quizNumber].answersByAdmin[0]
    ) {
      if (state.omrWithAnswers[page][quizNumber].answersByAdmin[0].answer === index) {
        return <CheckedIcon src='/images/quiz_answer.svg' />;
      }
      if (
        state.omrWithAnswers[page][quizNumber].answersByUser[0].answer !==
          state.omrWithAnswers[page][quizNumber].answersByAdmin[0].answer &&
        index === state.omrWithAnswers[page][quizNumber].answersByUser[0].answer
      ) {
        return <CheckedIcon src='/images/quiz_wrong.svg' />;
      }
    }
  };

... return (
  </QuizOptionImageWrap>
   {checkAnswer(index)}
</QuizOptionImageWrap>

위와같이 조건이 길어진 조건부 렌더링에서 함수로 뽑아서 사용한다.