vue3+elementplus后台管理系统，实现侧边栏菜单显示到主内容区域

import { createRouter, createWebHistory } from 'vue-router';
import HomePage from '@/views/HomePage.vue';
import CategroyPage from '@/views/CategoryPage.vue';
import ProductPage from '@/views/ProductPage.vue';
import IndexPage from '@/views/IndexPage.vue';
const routes = [
  {
    path: '/',
    component: HomePage,
    redirect:"index",
    children: [
      {
        path:'/index',
        component:IndexPage
      },
      {
      path: '/category',
      component: CategroyPage
    }, {
      path: '/product',
      component: ProductPage
    }]
  },
  {
    path: '/category',
    component: CategroyPage
  }
];
const router = createRouter({
  history: createWebHistory(),
  routes
});
export default router;

<el-menu :default-active="activeMenu" class="menu" router>
          <el-menu-item index="index">首页</el-menu-item>
          <el-sub-menu index="management" v-if="showManagement">
            <template #title>分类管理</template>
            <el-menu-item index="category">商品分类</el-menu-item>
            <el-menu-item index="product">商品管理</el-menu-item>
          </el-sub-menu>
          <el-sub-menu index="system" v-if="showSystem">
            <template #title>系统管理</template>
            <el-menu-item index="user">用户管理</el-menu-item>
            <el-menu-item index="role">角色管理</el-menu-item>
            <el-menu-item index="menu">菜单管理</el-menu-item>
          </el-sub-menu>
        </el-menu>

<el-main class="content">
        <!-- 放置表格 -->
        <router-view/>
      </el-main>

<template>
  <el-container class="admin-home">
    <el-aside width="200px">
      <el-scrollbar>
        <el-menu :default-active="activeMenu" class="menu" router>
          <el-menu-item index="index">首页</el-menu-item>
          <el-sub-menu index="management" v-if="showManagement">
            <template #title>分类管理</template>
            <el-menu-item index="category">商品分类</el-menu-item>
            <el-menu-item index="product">商品管理</el-menu-item>
          </el-sub-menu>
          <el-sub-menu index="system" v-if="showSystem">
            <template #title>系统管理</template>
            <el-menu-item index="user">用户管理</el-menu-item>
            <el-menu-item index="role">角色管理</el-menu-item>
            <el-menu-item index="menu">菜单管理</el-menu-item>
          </el-sub-menu>
        </el-menu>
      </el-scrollbar>
    </el-aside>
    <el-container>
      <el-header class="top">
        <div class="logo">
          <!-- 放置图标 -->
          <el-icon><Fold /></el-icon>
        </div>
        <div class="user-info" @click="toggleSubMenu">
          {{ userName }}
          <el-dropdown v-model="subMenuVisible">
            <el-icon><CaretBottom /></el-icon>
            <template #dropdown>
              <el-dropdown-menu>
                <el-dropdown-item>个人中心</el-dropdown-item>
                <el-dropdown-item divided>退出登录</el-dropdown-item>
              </el-dropdown-menu>
            </template>
          </el-dropdown>
        </div>
      </el-header>
      <el-main class="content">
        <!-- 放置表格 -->
        <router-view/>
      </el-main>
      <el-footer class="footer">
        版权信息
      </el-footer>
    </el-container>
  </el-container>
</template>
<script>
export default {
  data() {
    return {
      activeMenu: 'index',
      showManagement: true,
      showSystem: true,
      userName: 'John Doe',
      subMenuVisible: false,
    };
  },
  methods: {
    toggleSubMenu() {
      this.subMenuVisible = !this.subMenuVisible;
    },
  },
};
</script>
<style>
.admin-home {
  height: 100vh;
}
.top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.logo {
  /* 样式 */
}
.user-info {
  cursor: pointer;
}
.content {
  /* 样式 */
}
.footer {
  /* 样式 */
}
</style>