/* 安装依赖 */
// 安装element-ui
npm i element-ui -S
// 安装vue-fragment
npm i -s vue-fragment


/* main.js 引入 */
import Vue from 'vue';
// 引用element-ui
import ElementUI from 'element-ui';
import 'element-ui/lib/theme-chalk/index.css';
// 引用vue-fragment
import { Plugin } from 'vue-fragment'
Vue.use(Plugin)

<template>
    <fragment v-if="!item.hidden">
        <el-submenu
            v-if="item.children && item.children.length"
            :index="item.label"
        >
            <template slot="title">
                <i :class="item.icon"/>
                {{ item.label }}
            </template>

            <sidebar-item
        v-for="child in item.children"
                @item-click="(i) => $emit('item-click', i)"
        :key="child.path"
        :item="child"
      />
        </el-submenu>

        <el-menu-item
            v-else
            :index="item.url"
            @click="$emit('item-click', item)">
            <i :class="item.icon"/>
            {{ item.label }}
        </el-menu-item>
    </fragment>
</template>

<script>
export default {
  name: 'SidebarItem',
  props: {
    item: {
      type: Object,
      required: true
    }
  },
  methods: {
    handleItemClick (item) {
      this.$emit('item-click', item)
    }
  }
}
</script>

<template>
  <el-menu :default-active="activeIndex" unique-opened @select="handleLoadUrl">
    <sidebar-item v-for="item in menuList" :key="item.path" :item="item" @item-click="handleItemClick"/>
  </el-menu>
</template>

<script>
import SidebarItem from './sidebarItem.vue'
export default {
  components: { SidebarItem },
  data () {
    return {
      activeIndex: '/1',
      menuList: [
        {
          label: '一级菜单1',
          icon: 'el-icon-s-help',
          url: '/1'
        },
        {
          label: '一级菜单2',
          icon: 'el-icon-s-help',
          url: '/2',
          children: [
              { label: '二级菜单2.1', url: '/2/1' }
          ]
        }
      ]
    }
  },
  watch: {
    $route: {
      handler: function (to, from) {
        this.$nextTick(() => {
          if (to) {
            this.activeIndex = to.path
          }
        })
        // console.log(to, from)
      },
      immediate: true
    }
  },
  created () {
  },
  mounted () {},
  methods: {
    handleLoadUrl (index, indexPath) {
      // console.log(index, indexPath, 5566)
    },
    handleItemClick (item) {
      const { url, label } = item
      this.activeIndex = url || label
      this.$router.push(this.activeIndex)
    }
  }
}
</script>