Vue-cli routing children have no rendering effect?

problem description

RT, secondary setting rendering will turn the children into that component. No matter what level 3 is set, it has always been a rendering HelloWorld component. Is there something wrong with my configuration?

related codes

template

<el-menu :default-active="activeMenuIndex" class="el-menu-vertical-demo"
background-color="-sharp22205f" text-color="-sharpfff" active-text-color="-sharpff9c02"
router>
    <el-menu-item v-for="item1 in menuData" :key="item1.path" :index="item1.path"
    v-if="item1.children==undefined">
        <i :class="item1.icon">
        </i>
        <span>
            {{item1.name}}
        </span>
    </el-menu-item>
    <el-submenu v-for="item2 in menuData" :key="item2.path" :index="item2.path"
    v-if="item2.children!=undefined">
        <template slot="title">
            <i :class="item2.icon">
            </i>
            <span>
                {{item2.name}}
            </span>
        </template>
        <el-menu-item v-for="item3 in item2.children" :key="item3.path" :index="item3.path"
        v-if="item3.children==undefined">
            {{item3.name}}
        </el-menu-item>
        <el-submenu v-for="item4 in item2.children" :key="item4.path" :index="item4.path"
        v-if="item4.children!=undefined">
            <template slot="title">
                {{item4.name}}
            </template>
            <el-menu-item v-for="item5 in item4.children" :key="item5.path" :index="item5.path">
                {{item5.name}}
            </el-menu-item>
        </el-submenu>
    </el-submenu>
</el-menu>

routing:

{
      path: "/nhsj",
      name: "",
      icon: "fas fa-burn",
      component: HelloWorld,
      children: [{
        path: "/nhsj/nhgs",
        name: "",
        component: HelloWorld,
      }, {
        path: "/nhsj/nhsj",
        name: "",
        component: HelloWorld,
      }, {
        path: "/nhsj/nhfx",
        name: "",
        component: HelloWorld,
        children: [{
          path: "/nhsj/nhfx/nnytj",
          name: "",
          component: a1,
        }, {
          path: "/nhsj/nhfx/ynytj",
          name: "",
          component: HelloWorld,
        }, {
          path: "/nhsj/nhfx/nydb",
          name: "",
          component: HelloWorld,
        }, {
          path: "/nhsj/nhfx/fgzsjnydb",
          name: "",
          component: HelloWorld,
        }, {
          path: "/nhsj/nhfx/nyfl",
          name: "",
          component: HelloWorld,
        }]
      }, {
        path: "/nhsj/nhkh",
        name: "",
        component: HelloWorld,
      }]
    }

what result do you expect? What is the error message actually seen?

specify the component based on my route rendering. Now level 3 only renders helloword, II only components of the first level menu.

Dec.10,2021
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