类组件不等待函数返回

class MyComponent extends React.Component {
  componentDidMount() {
    this.fetchData();
  }

  fetchData() {
    fetch('https://api.example.com/data')
      .then(response => response.json())
      .then(data => {
        this.setState({ data });
      })
      .catch(error => {
        console.error('Error fetching data:', error);
      });
  }

  render() {
    return (
      <div>
        {this.state.data ? <p>{this.state.data.message}</p> : <p>Loading...</p>}
      </div>
    );
  }
}

class MyComponent extends React.Component {
  async componentDidMount() {
    try {
      const data = await this.fetchData();
      this.setState({ data });
    } catch (error) {
      console.error('Error fetching data:', error);
    }
  }

  fetchData() {
    return fetch('https://api.example.com/data')
      .then(response => response.json());
  }

  render() {
    return (
      <div>
        {this.state.data ? <p>{this.state.data.message}</p> : <p>Loading...</p>}
      </div>
    );
  }
}