1. react, react-dom 설치
    npm install --save react
    npm install --save react-dom
    router 추가 설치시
    npm install --save react-router-dom
  1. src/index.js 폴더에 리액트 삽입

    import React from 'react';
    import ReactDOM from 'react-dom';
    const title = 'Hello world!!';
    ReactDOM.render(
    <div>{title}</div>,
    document.getElementById('example')
    );
  2. npm start 로 확인