vue+element实现页面顶部tag思路详解

 addTag: (state, tag) => {
    const { fullPath, path, meta, query } = tag
    if (tag.path === '/login') {
      return false
    }
    const findIndex = state.tags.findIndex(item => item.path === tag.path)
    console.log(findIndex)
    if (findIndex >= 0) {
      state.tags.splice(findIndex, 1, { fullPath, path, meta, query })
    } else {
      state.tags.push({ fullPath, path, meta, query })
    }
  },

computed: {
currentRoute() {
      return this.$route
    },
},
 watch: {
    $route: {
      handler(val) {
        if (val.name) {
          this.addTags()
        }
      },
      // 深度观察监听
      deep: true
    }
  },
  methods:{
  addTags() {
  //this.$store.dispatch 先提交给action，由他异步处理处罚mutation里面的方法，改变state里面的tags值
      this.$store.dispatch('user/addTag', this.currentRoute)
    },}

<span v-for="(tag, index) in tags" :key="index" class="tag-span">
        <el-tag
          :closable="isCloseable"
          :effect="setTagColor(tag)"
          @close="closeTags(tag)"
          @click="toTagRoute(tag)"
        >
          {{ tag.meta.title }}
        </el-tag>
      </span>
 methods:{
 setTagColor(tag) {
      return this.currentRoute.path === tag.path ? 'dark' : 'plain'
    },
    }

methods:{
 toTagRoute(tag) {
      this.$router.push({
        path: tag.fullPath || tag.path
      })
    },
}

methods:{
	 closeTags(tag) {
	      console.log(tag, 4444)
	      this.$store.dispatch('user/delTag', tag)
	      this.toLastTagRouter(this.$store.state.user.tags)//高亮删除标签的前一个tag
	    },
     toLastTagRouter(tags) {
      //注意此处传入tags是已删除后的，所以不能使用splice==》改变原数组；slice==》不改变原数组拿去数组最后一个元素
      const latestView = tags.slice(-1)[0]//tags数组最后一个元素
      console.log(latestView)
      if (latestView !== undefined && latestView.path !== undefined) {
        const { fullPath, meta, path, query } = latestView
        this.$router.push({ fullPath, meta, path, query })
      }
    },
}
//action
 delTag({ commit }, tag) {
    commit('delTag', tag)
  },
//mutation
delTag: (state, tag) => {
    //entries()对象变成一个可遍历的数组【0，{name:a,age:'20'}】
    //这里使用forEach和map也可以
    for (const [i, v] of state.tags.entries()) {
      if (v.path === tag.path) {
        state.tags.splice(i, 1)
        break
      }
    }
  },

methods:{
 closeAllTags() {
      // 关闭所有 tag，仅剩余一个
      this.$store.dispatch('user/delAllTags')
      const { fullPath, meta, path, query } = this.$store.state.user.tags[0]
      // 跳转剩余 tag 路由
      this.$router.push({ fullPath, meta, path, query })
    },
}
//action
delAllTags({ commit }) {
    commit('delAllTags')
  },
//mutation
 delAllTags: (state) => {
    state.tags.splice(1, state.tags.length)
  },