在整个应用程序中仅加载一次组件

class SingletonComponent extends React.Component {
  constructor(props) {
    super(props);
    if (!SingletonComponent.instance) {
      SingletonComponent.instance = this;
    }
    return SingletonComponent.instance;
  }

  render() {
    return <div>This is a singleton component</div>;
  }
}

// Usage
const ComponentA = () => <SingletonComponent />;
const ComponentB = () => <SingletonComponent />;

class SingletonComponent extends React.Component {
  static instance = null;

  constructor(props) {
    super(props);
    if (!SingletonComponent.instance) {
      SingletonComponent.instance = this;
    }
    return SingletonComponent.instance;
  }

  render() {
    return <div>This is a singleton component</div>;
  }
}