通过fetch方法获取时，组件的数据属性不是反应性的

import React, { Component } from 'react';

class MyComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      data: null
    };
  }

  async componentDidMount() {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    this.setState({ data });
  }

  render() {
    const { data } = this.state;
    return (
      <div>
        {data ? (
          <ul>
            {data.map(item => (
              <li key={item.id}>{item.name}</li>
            ))}
          </ul>
        ) : (
          <p>Loading...</p>
        )}
      </div>
    );
  }
}

export default MyComponent;