配置elementuI菜单

:unique-opened="true" 只保留一个菜单

:router="true"开启路由标识

index="users" 是标识 它就会去找这个路由

          
  <el-menu
    default-active="2"
    :router="true"
    :unique-opened="true"
    class="el-menu-vertical-demo"
    @open="handleOpen"
    @close="handleClose"
    background-color="#d3dce6"
    text-color="#fff"
    active-text-color="#ffd04b"
  >

   标识
   <el-menu-item-group>
    <el-menu-item index="users">用户列表</el-menu-item>
    <el-menu-item index="1-2">选项2</el-menu-item>
  </el-menu-item-group>

路由
 {
      path: "/home",
      name: "home",
      component: () => import("../components/home/home.vue"),
      children: [
        {
          path: "/users",
          name: "users",
          component: () => import("../components/users/users.vue")
        }
      ]
    }