[
  {
   "id": "1",
   "menuName": "基础管理",
   "menuCode": "10",
   "children": [
    {
     "menuName": "用户管理",
     "menuCode": "11"
    },
    {
     "menuName": "角色管理",
     "menuCode": "12",
     "children": [
      {
       "menuName": "管理员",
       "menuCode": "121"
      },
      {
       "menuName": "CEO",
       "menuCode": "122"
      },
      {
       "menuName": "CFO",
       "menuCode": "123"
      },
      {
       "menuName": "COO",
       "menuCode": "124"
      },
      {
       "menuName": "普通人",
       "menuCode": "124"
      }
     ]
    },
    {
     "menuName": "权限管理",
     "menuCode": "13"
    }
   ]
  },
  {
   "id": "2",
   "menuName": "商品管理",
   "menuCode": ""
  },
  {
   "id": "3",
   "menuName": "订单管理",
   "menuCode": "30",
   "children": [
    {
     "menuName": "订单列表",
     "menuCode": "31"
    },
    {
     "menuName": "退货列表",
     "menuCode": "32",
     "children": []
    }
   ]
  },
  {
   "id": "4",
   "menuName": "商家管理",
   "menuCode": "",
   "children": []
  }
 ]

<template>
 <li>
  <span @click="toggle">   <!-- toggle:点击关闭展开 -->
   <i v-if="isFolder" class="icon" :class="[open " @cilck="toggle"></i>
   <!-- <i v-if="isFolder" class="icon " :class="[open "></i> -->
   <i v-if="!isFolder" class="icon folder-text"></i>
   {{model.menuName}}
  </span>
  <ul v-show="open" v-if="isFolder">
   <treeMenu v-for="item in model.children" :model="item"></treeMenu>
  </ul>
 </li>
</template>

export default {
  name: 'treeMenu',
  //props: ['model'], //这样和下面效果一样
  props: {
   model: { type: Object },
  },
  components: {},
}

  data() {
   return {
    open: false, //一个显示隐藏子菜单(open)
    //isFolder: true  //这个不要写死，运用计算属性计算看存不存在
   }
  },

  computed: {
   isFolder() { //利用vue计算属性动态改变isFolder的值，修改图标，判断存在不子级和子级长度
    // return this.model.children && this.model.children.length //和下面效果一样
    let isFolder = false
    if (this.model.children && this.model.children.length) {
     isFolder = true;
    } else {
     isFolder = false;
    }
    return isFolder
   }
  },

  methods: {
   toggle() {
    if (this.isFolder) {
     this.open = !this.open
    }
   }
  },