Menu: add popper-class for SubMenu (#9600)

examples/docs/en-US/menu.md

@@ -305,6 +305,7 @@ Vertical NavMenu could be collapsed.
 | Attribute      | Description          | Type      | Accepted Values       | Default  |
 |---------- |-------- |---------- |-------------  |-------- |
 | index     | unique identification   | string  | — | — |
+| popper-class | custom class name for the popup menu | string | — | — |
 | show-timeout | timeout before showing a sub-menu | number | — | 300 |
 | hide-timeout | timeout before hiding a sub-menu | number | — | 300 |
 

examples/docs/es/menu.md

@@ -307,6 +307,7 @@ NavMenu vertical puede ser colapsado.
 | Atributo     | Descripción                              | Tipo   | Valores aceptados | Por defecto |
 | ------------ | ---------------------------------------- | ------ | ----------------- | ----------- |
 | index        | identificador único                      | string | —                 | —           |
+| popper-class | custom class name for the popup menu     | string | —                 | —           |
 | show-timeout | tiempo de espera antes de mostrar un submenú | number | —                 | 300         |
 | hide-timeout | tiempo de espera antes de ocultar un submenú | number | —                 | 300         |
 

examples/docs/zh-CN/menu.md

@@ -301,6 +301,7 @@
 | 参数      | 说明    | 类型      | 可选值       | 默认值   |
 |---------- |-------- |---------- |-------------  |-------- |
 | index     | 唯一标志   | string  | — | — |
+| popper-class | 弹出菜单的自定义类名 | string | — | — |
 | show-timeout | 展开 sub-menu 的延时 | number | — | 300 |
 | hide-timeout | 收起 sub-menu 的延时 | number | — | 300 |
 

packages/menu/src/submenu.vue

@@ -41,7 +41,8 @@
       hideTimeout: {
         type: Number,
         default: 300
-      }
+      },
+      popperClass: String
     },
 
     data() {
@@ -223,7 +224,8 @@
         rootMenu,
         currentPlacement,
         menuTransitionName,
-        mode
+        mode,
+        popperClass
       } = this;
 
       const popupMenu = (
@@ -231,7 +233,7 @@
           <div
             ref="menu"
             v-show={opened}
-            class={[`el-menu--${mode}`]}
+            class={[`el-menu--${mode}`, popperClass]}
             on-mouseenter={this.handleMouseenter}
             on-mouseleave={this.handleMouseleave}
             on-focus={this.handleMouseenter}>