React simple diary - 최적화 완성

useEffect, React.memo, useCallback을 이용해 최적화 완료 :)

App.js

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import "./App.css";
import DiaryEditor from "./DiaryEditor";
import DiaryList from "./DiaryList";

function App() {
  const [data, setData] = useState([]);

  const dataId = useRef(0);

  const getData = async () => {
    const res = await fetch(
      "https://jsonplaceholder.typicode.com/comments"
    ).then((res) => res.json());

    const initData = res.slice(0, 20).map((it) => {
      return {
        author: it.email,
        content: it.body,
        emotion: Math.floor(Math.random() * 5) + 1,
        created_date: new Date().getTime(),
        id: dataId.current++,
      };
    });

    setData(initData);
  };

  useEffect(() => {
    getData();
  }, []);

  const onCreate = useCallback((author, content, emotion) => {
    const created_date = new Date().getTime();
    const newItem = {
      author,
      content,
      emotion,
      created_date,
      id: dataId.current,
    };
    dataId.current += 1;

    setData((data) => [newItem, ...data]);
  }, []);

  const onRemove = useCallback((targetId) => {
    // 최신 state를 이용하기 위해선 항상 인자 부분에 data를 사용해 줘야 함
    setData((data) => data.filter((it) => it.id !== targetId));
  }, []);

  const onEdit = useCallback((targetId, newContent) => {
    setData((data) =>
      data.map((it) =>
        it.id === targetId ? { ...it, content: newContent } : it
      )
    );
  }, []);

  const getDiaryAnalysis = useMemo(() => {
    const goodCount = data.filter((it) => it.emotion >= 3).length;
    const badCount = data.length - goodCount;
    const goodRatio = (goodCount / data.length) * 100;
    return { goodCount, badCount, goodRatio };
  }, [data.length]);

  const { goodCount, badCount, goodRatio } = getDiaryAnalysis;

  return (
    <div className="App">
      <DiaryEditor onCreate={onCreate} />
      <div>전체일기 : {data.length}</div>
      <div>기분 좋은 일기 갯수 : {goodCount}</div>
      <div>기분 나쁜 일기 갯수 : {badCount}</div>
      <div>기분 좋은 일기 비율 : {goodRatio}</div>
      <DiaryList onEdit={onEdit} onRemove={onRemove} diaryList={data} />
    </div>
  );
}
export default App;

DiaryEditor.js

import React, { useEffect, useRef, useState } from "react";

const DiaryEditor = ({ onCreate }) => {
  const authorInput = useRef();
  const contentInput = useRef();

  const [state, setState] = useState({
    author: "",
    content: "",
    emotion: 1,
  });

  const handleChangeState = (e) => {
    setState({
      ...state,
      [e.target.name]: e.target.value,
    });
  };

  const handleSubmit = () => {
    if (state.author.length < 1) {
      authorInput.current.focus();
      return;
    }

    if (state.content.length < 5) {
      contentInput.current.focus();
      return;
    }

    onCreate(state.author, state.content, state.emotion);
    alert("저장 성공");
    setState({
      author: "",
      content: "",
      emotion: 1,
    });
  };

  return (
    <div className="DiaryEditor">
      <h2>오늘의 일기</h2>
      <div>
        <input
          ref={authorInput}
          name="author"
          value={state.author}
          onChange={handleChangeState}
        />
      </div>
      <div>
        <textarea
          ref={contentInput}
          name="content"
          value={state.content}
          onChange={handleChangeState}
        />
      </div>
      <div>
        <select
          name="emotion"
          value={state.emotion}
          onChange={handleChangeState}
        >
          <option value={1}>1</option>
          <option value={2}>2</option>
          <option value={3}>3</option>
          <option value={4}>4</option>
          <option value={5}>5</option>
        </select>
      </div>
      <div>
        <button onClick={handleSubmit}>일기 저장하기</button>
      </div>
    </div>
  );
};

export default React.memo(DiaryEditor);

DiaryItem.js

import React, { useEffect, useRef, useState } from "react";

const DiaryItem = ({
  onRemove,
  onEdit,
  id,
  author,
  content,
  emotion,
  created_date,
}) => {
  // useEffect를 이용해 어떤 아이템들이 rerendering되고 있는지 확인
  useEffect(() => {
    console.log(`${id}번째 아이템 렌더`);
  });

  const [isEdit, setIsEdit] = useState(false);
  const toggleIsEdit = () => setIsEdit(!isEdit);

  const [localContent, setLocalContent] = useState(content);

  const localContentInput = useRef();

  const handleRemove = () => {
    if (window.confirm(`${id}번째 일기를 정말 삭제하시겠습니까?`)) {
      onRemove(id);
    }
  };

  const handleQuitEdit = () => {
    setIsEdit(false);
    setLocalContent(content);
  };

  const handleEdit = () => {
    if (localContent.length < 5) {
      localContentInput.current.focus();
      return;
    }

    if (window.confirm(`${id}번 째 일기를 수정하시겠습니까?`)) {
      onEdit(id, localContent);
      toggleIsEdit();
    }
  };

  return (
    <div className="DiaryItem">
      <div className="info">
        <span className="author_info">
          | 작성자 : {author} | 감정점수 : {emotion} |
        </span>
        <br />
        <span className="date">{new Date(created_date).toLocaleString()}</span>
      </div>
      <div className="content">
        {isEdit ? (
          <>
            <textarea
              ref={localContentInput}
              value={localContent}
              onChange={(e) => setLocalContent(e.target.value)}
            />
          </>
        ) : (
          <>{content}</>
        )}
      </div>

      {isEdit ? (
        <>
          <button onClick={handleQuitEdit}>수정취소</button>
          <button onClick={handleEdit}>수정완료</button>
        </>
      ) : (
        <>
          <button onClick={handleRemove}>삭제하기</button>
          <button onClick={toggleIsEdit}>수정하기</button>
        </>
      )}
    </div>
  );
};

export default React.memo(DiaryItem);

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