text: 
  import React from 'react';
  import ReactDOM from 'react-dom';
  import ChangeButton from './components/change-button';
  
  const App = () => {
    return (
      <div>
        <ChangeButton />
      </div>
    );
  }
  
  // 要实现局部热更新，必须添加如下代码
  if (module.hot) {
    module.hot.accept();
  }
  
  ReactDOM.render(<App />, document.getElementById('root'));