ant-design/components/cascader/demo/hover.md

order	title
2	移入展开

通过移入展开下级菜单，点击完成选择。

import { Cascader } from 'antd';

const options = [{
  value: 'zhejiang',
  label: '浙江',
  children: [{
    value: 'hangzhou',
    label: '杭州',
    children: [{
      value: 'xihu',
      label: '西湖',
    }],
  }],
}, {
  value: 'jiangsu',
  label: '江苏',
  children: [{
    value: 'nanjing',
    label: '南京',
    children: [{
      value: 'zhonghuamen',
      label: '中华门',
    }],
  }],
}];

function onChange(value) {
  console.log(value);
}

// 只展示最后一项
function displayRender(label) {
  return label[label.length - 1];
}

ReactDOM.render(
  <Cascader options={options} expandTrigger="hover"
    displayRender={displayRender} onChange={onChange} />
, mountNode);