React变量更改，但它不应该

class MyComponent extends React.Component {
  shouldComponentUpdate(nextProps, nextState) {
    // 比较当前状态和下一个状态，决定是否重新渲染
    return this.state.someValue !== nextState.someValue;
  }

  render() {
    return <div>{this.state.someValue}</div>;
  }
}

const MyComponent = React.memo(function MyComponent({ someValue }) {
  return <div>{someValue}</div>;
}, (prevProps, nextProps) => {
  // 比较前后 props，决定是否重新渲染
  return prevProps.someValue === nextProps.someValue;
});

import React, { useState, useEffect } from 'react';

function MyComponent() {
  const [someValue, setSomeValue] = useState(initialValue);

  useEffect(() => {
    // 副作用逻辑
    const handleAsyncOperation = async () => {
      const result = await someAsyncFunction();
      if (result !== someValue) {
        setSomeValue(result);
      }
    };

    handleAsyncOperation();

    return () => {
      // 清理逻辑
    };
  }, [someValue]); // 依赖数组，确保只在 someValue 变化时运行

  return <div>{someValue}</div>;
}

class MyComponent extends React.Component {
  state = {
    someValue: initialValue,
  };

  componentDidUpdate(prevProps, prevState) {
    console.log('Previous state:', prevState);
    console.log('Current state:', this.state);
  }

  render() {
    return <div>{this.state.someValue}</div>;
  }
}