reactjs获取元素的子级计数

import React from 'react';

class ParentComponent extends React.Component {
  render() {
    const childCount = React.Children.count(this.props.children);
    return (
      <div>
        <h1>子级计数：{childCount}</h1>
        {this.props.children}
      </div>
    );
  }
}

class ChildComponent extends React.Component {
  render() {
    return <p>子组件</p>;
  }
}

// 在其他组件中使用ParentComponent，并传入子组件
class App extends React.Component {
  render() {
    return (
      <ParentComponent>
        <ChildComponent />
        <ChildComponent />
        <ChildComponent />
      </ParentComponent>
    );
  }
}

export default App;