componentdidupdate

import React, { Component } from 'react';

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

  componentDidMount() {
    this.fetchData(this.props.id);
  }

  componentDidUpdate(prevProps) {
    // 当 id 发生变化时，重新获取数据
    if (prevProps.id !== this.props.id) {
      this.fetchData(this.props.id);
    }
  }

  fetchData(id) {
    fetch(`https://api.example.com/data/${id}`)
      .then(response => response.json())
      .then(data => {
        this.setState({ data });
      });
  }

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

export default MyComponent;

componentDidUpdate(prevProps, prevState) {
  if (prevState.someValue !== this.state.someValue) {
    this.setState((prevState) => ({
      someValue: prevState.someValue + 1,
    }));
  }
}

shouldComponentUpdate(nextProps, nextState) {
  return nextProps.id !== this.props.id || nextState.data !== this.state.data;
}