import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

export default new Vuex.Store({
  state: {
    tabList:[]
  },
  mutations: {
    addTab: (state, tab) => {
      // 如果tab已經(jīng)存在，不添加新的tabs
      if (state.tabList.some(item => item.path === tab.path)) return
      state.tabList.push(tab)
    }
  },
  getters: {
    // 獲取tbsList
    getTabs: (state) => {
      return state.tabList
    }
  },
  actions: {
  },
  modules: {
  }
})

<template>
  <el-tabs
    v-model="activeTab"
    closable
    @tab-remove="removeTab"
    @tab-click="clickBtn"
  >
    <el-tab-pane
      :key="index"
      v-for="(item, index) in tabList"
      :label="item.title"
      :name="item.path"
    >
      {{ item.content }}
    </el-tab-pane>
  </el-tabs>
</template>

<script>
import store from '../../store'
export default {
  name: '',
  data() {
    return {
      // 當(dāng)前活躍的tabs
      activeTab: '',
    }
  },
  components: {},
  computed: {
    tabList() {
      return store.getters['getTabs']
    },
  },
  watch: {
    $route: function () {
      this.setActiveTab()
      this.addTab()
    },
  },
  created() {},
  mounted() {
    this.beforeRefresh()
    this.setActiveTab()
    this.addTab()
  },
  methods: {
    // 設(shè)置活躍的tab
    setActiveTab() {
      this.activeTab = this.$route.path
    },
    // 添加tab
    addTab() {
      const { path, meta } = this.$route
      const tab = {
        path,
        title: meta.title,
      }
      store.commit('addTab', tab)
    },
    // 點擊tab
    clickBtn(tab) {
      const { name } = tab
      this.$router.push({ path: name })
    },
    // 刪除tab
    removeTab(target) {
      // 當(dāng)前激活的tab
      let active = this.activeTab
      const tabs = this.tabList
      // 只有一個標(biāo)簽頁的時候不允許刪除
      if (tabs.length === 1) return
      if (active === target) {
        tabs.forEach((tab, index) => {
          // 如果刪除的就是當(dāng)前活躍的tab,就把活躍的tab變成上一個或下一個
          const nextTab = tab[index + 1] || tab[index - 1]
          if (nextTab) {
            active = nextTab.path
          }
        })
      }
      // 重新設(shè)置當(dāng)前激活的選項卡和 選項卡列表
      this.activeTab = active
      store.state.tabList = tabs.filter((tab) => tab.path !== target)
    },
    // 解決刷新數(shù)據(jù)丟失問題
    beforeRefresh() {
      window.addEventListener('beforeunload', () => {
        sessionStorage.setItem('tabsView', JSON.stringify(this.tabList))
      })
      let tabSession = sessionStorage.getItem('tabsView')
      if (tabSession) {
        let oldTabs = JSON.parse(tabSession)
        if (oldTabs.length > 0) {
          store.state.tabList = oldTabs
        }
      }
    },
  },
}
</script>

{
    path: '/layout',
    component: () => import('../layout/index.vue'),
    children: [
      {
        path: 'lay1',
        component: () => import('../views/lay/Lay1.vue'),
        meta: {
          title:'選項1'
        }
      },
      {
        path: 'lay2',
        component: () => import('../views/lay/Lay2.vue'),
        meta: {
          title:'選項2'
        }
        
      },
      {
        path: 'lay3',
        component: () => import('../views/lay/Lay3.vue'),
        meta: {
          title:'選項3'
        }
      },
      {
        path: 'lay4',
        component: () => import('../views/lay/Lay4.vue'),
        meta: {
          title:'選項4'
        }
      },
    }