#### 触发事件
点击菜单项后会触发事件，用户可以通过相应的菜单项 key 进行不同的操作。
#### Click event
An event will be triggered when you click menu items, in which you can make different operations according to item's key.
```html
Hover me, Click menu item
1st menu item
2nd menu item
3rd menu item
```