React event binding details

import React from 'react';
import ReactDOM from 'react-dom';
class App extends React.Component {
  handleClick() {
    console.log(111);
  }
  render() {
    return (<button onClick={this.handleClick} > Click me</button >)
  }
}
ReactDOM.render(<App />, document.getElementById('root'))

import React from 'react';
import ReactDOM from 'react-dom';
function App() {
  function handleClick() {
    console.log(111);
  }
  // There is no this in the function component, so just write the function name without adding this.
  return (<button onClick={handleClick}>Click me</button>)
}
ReactDOM.render(<App />, document.getElementById('root'))