按需引入封装的组件

export function asyncComponent (importComponent) {
  class AsyncComponent extends React.Component {
    constructor (props) {
      super(props);
 
      this.state = {
        component: null
      };
    }
 
    componentDidMount () {
      importComponent()
        .then(cmp => {
          this.setState({ component: cmp.default });
        });
    }
 
    render () {
      const C = this.state.component;
 
      return C ? <C {...this.props} /> : null;
    }
  }
 
  return AsyncComponent;
}