React更新setInterval中的属性工作两次

import React, { useEffect } from "react";

const MyComponent = () => {
  useEffect(() => {
    const timer = setInterval(() => {
      // 执行定时任务
    }, 1000);
    
    return () => {
      clearInterval(timer);
    };
  }, []); // 依赖数组为空，表示只在组件挂载时执行一次

  return (
    // 组件的 JSX
  );
};

export default MyComponent;

import React, { Component } from "react";

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

  componentDidMount() {
    this.timer = setInterval(() => {
      // 执行定时任务
    }, 1000);
  }

  componentWillUnmount() {
    clearInterval(this.timer);
  }

  render() {
    return (
      // 组件的 JSX
    );
  }
}

export default MyComponent;