feat: allow string type z-index

src/dropdown-menu/README.md

@@ -113,7 +113,7 @@ Use `active-color` prop to custom active color of the title and options
 | Attribute | Description | Type | Default |
 |------|------|------|------|
 | active-color | Active color of title and option | *string* | `#1989fa` |
-| z-index | z-index of menu item | *number* | `10` |
+| z-index | z-index of menu item | *string \| number* | `10` |
 | duration | Transition duration, unit second | *number* | `0.2` |
 | direction `v2.0.1` | Expand direction, can be set to `up` | *string* | `down` |
 | overlay | Whether to show overlay | *boolean* | `true` |

src/dropdown-menu/README.zh-CN.md

@@ -117,7 +117,7 @@ export default {
 | 参数 | 说明 | 类型 | 默认值 |
 |------|------|------|------|
 | 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` |
+| z-index | 菜单栏 z-index 层级 | *string \| number* | `10` |
 | duration | 动画时长，单位秒 | *number* | `0.2` |
 | direction `v2.0.1` | 菜单展开方向，可选值为`up` | *string* | `down` |
 | overlay | 是否显示遮罩层 | *boolean* | `true` |

src/dropdown-menu/index.js

@@ -19,7 +19,7 @@ export default createComponent({
   ],
 
   props: {
-    zIndex: Number,
+    zIndex: [Number, String],
     activeColor: String,
     overlay: {
       type: Boolean,