[new feature] DropdownItem: add open & close event

packages/dropdown-item/index.js

@@ -63,6 +63,8 @@ export default sfc({
       );
     });
 
+    const emit = eventName => () => this.$emit(eventName);
+
     return (
       <div vShow={this.show} style={{ top: `${top}px`, zIndex }} class={bem()}>
         <Popup
@@ -73,6 +75,9 @@ export default sfc({
           overlay={overlay}
           closeOnClickOverlay={closeOnClickOverlay}
           overlayStyle={{ position: 'absolute' }}
+          onOpen={emit('open')}
+          onOpened={emit('opened')}
+          onClose={emit('close')}
         >
           {Options}
           {this.slots('default')}

packages/dropdown-menu/en-US.md

@@ -98,6 +98,9 @@ export default {
 | Event | Description | Arguments |
 |------|------|------|
 | change | Triggered select option and value changed | value |
+| open | Triggered when open menu | - |
+| opened | Triggered when opened menu | - |
+| close | Triggered when close menu | - |
 
 ### DropdownItem Methods
 

packages/dropdown-menu/zh-CN.md

@@ -100,6 +100,9 @@ export default {
 | 事件名 | 说明 | 回调参数 |
 |------|------|------|
 | change | 点击选项导致 value 变化时触发 | value |
+| open | 打开菜单栏时触发 | - |
+| opened | 打开菜单栏且动画结束后触发 | - |
+| close | 关闭菜单栏时触发 | - |
 
 ### DropdownItem 方法