rc-dropdown@2.4.1

/* eslint-disable no-console */
import Dropdown from 'rc-dropdown';
import Menu, { Item as MenuItem } from 'rc-menu';
import 'rc-dropdown/assets/index.css';
import React, { PureComponent } from 'react';
import ReactDOM from 'react-dom';

class Example extends PureComponent {
  state = { longList: false };
  short = () => {
    this.setState({ longList: false });
  }
  long = () => {
    this.setState({ longList: true });
  }
  render() {
    const menuItems = [
      <MenuItem key="1">1st item</MenuItem>,
      <MenuItem key="2">2nd item</MenuItem>,
    ];

    if (this.state.longList) {
      menuItems.push(<MenuItem key="3">3rd LONG SUPER LONG item</MenuItem>);
    }
    const menu = (
      <Menu>
        {menuItems}
      </Menu>
    );
    return (
      <div>
        <Dropdown overlay={menu}>
          <button>
            Actions
          </button>
        </Dropdown>
        <button onClick={this.long}>Long List</button>
        <button onClick={this.short}>Short List</button>
      </div>
    );
  }
}

ReactDOM.render(
  <Example />,
  document.getElementById('__react-content')
);