[new feature] DropdownMenu: add duration prop

packages/dropdown-menu/en-US.md

@@ -84,6 +84,7 @@ export default {
 |------|------|------|------|------|
 | active-color | Active color of title and option | `String` | `#1989fa` |
 | z-index | z-index of menu item | `Number` | `10` |
+| duration | Transition duration, unit second | `Number` | `0.2` |
 | overlay | Whether to show overlay | `Boolean` | `true` |
 | close-on-click-overlay | Whether to close when click overlay | `Boolean` | `true` |
 

packages/dropdown-menu/index.js

@@ -20,6 +20,10 @@ export default sfc({
       type: Number,
       default: 10
     },
+    duration: {
+      type: Number,
+      default: 0.2
+    },
     activeColor: {
       type: String,
       default: BLUE

packages/dropdown-menu/zh-CN.md

@@ -95,6 +95,7 @@ export default {
 |------|------|------|------|------|
 | active-color | 菜单标题和选项的选中态颜色 | `String` | `#1989fa` | - |
 | z-index | 菜单栏 z-index 层级 | `Number` | `10` | - |
+| duration | 动画时长，单位秒 | `Number` | `0.2` | 2.0.0 |
 | overlay | 是否显示遮罩层 | `Boolean` | `true` | - |
 | close-on-click-overlay | 是否在点击遮罩层后关闭菜单 | `Boolean` | `true` | - |