vue 项目横向菜单item过多导致换行问题

问题：

解决方案：
菜单默认展示8个，超过8个时出现左右箭头，可以切换

代码实现：

<template>
  <div class="scrollbar">
    <!-- <el-scrollbar wrap-class="scrollbar-wrapper"> -->

    <el-row type="flex">

      <span v-if="showDrop" class="change">
        <!-- 项目切换 -->
        <projectMenu v-if="this.$route.params.projectKey " />
        <!-- 项目集切换 -->
        <pMMenu v-if="this.$route.params.projectmCode" />
        <!-- 产品切换 -->
        <productMenu v-if="this.$route.params.productCode" />
        <!-- 产品集切换 -->
        <productfitMenu v-if="this.$route.params.productfitId" />
        <!-- 资源中心切换 -->
        <sourceMenu v-if="this.$route.params.systemId" />
      </span>
      <el-menu :default-active="activeMenu" mode="horizontal">
        <div class="left">

          <i v-if="currentTabIndex" class="iconfont el-icon-icon-system-left" @click="menuleft" />

        </div>

        <sidebar-item v-for="(route,index) in currentAppMenu" v-show="index >= currentTabIndex && currentTabIndex + 8 > index " :key="route.path" :item="route" :base-path="route.path" />
        <div class="right">
          <i v-show="currentAppMenu.length - currentTabIndex > 8" class="iconfont el-icon-icon-system-right" @click="menuright" />
        </div>
      </el-menu>

    </el-row>
    <!-- </el-scrollbar> -->
  </div>
</template>

<script>
import { mapGetters } from 'vuex'
import SidebarItem from './SidebarItem'
import variables from '@/styles/variables.scss'
import projectMenu from './projectMenu.vue'
import pMMenu from './pMMenu.vue'
import productMenu from './productMenu.vue'
import productfitMenu from './productfitMenu.vue'
import sourceMenu from './sourceMenu.vue'

export default {
  components: { SidebarItem, projectMenu, pMMenu, productMenu, productfitMenu, sourceMenu },
  data() {
    return {
      showDrop: false,
      currentTabIndex: 0
    }
  },
  computed: {
    ...mapGetters([
      'currentAppMenu'
    ]),
    activeMenu() {
      const route = this.$route
      const { meta, path } = route
      // if set path, the sidebar will highlight the path you set
      if (meta.activeMenu) {
        return meta.activeMenu
      }
      return path
    },
    variables() {
      return variables
    }
  },
  mounted() {
    if (this.$route.params.projectKey || this.$route.params.projectmCode || this.$route.params.productCode || this.$route.params.productfitId || this.$route.params.systemId) {
      this.showDrop = true
    } else {
      this.showDrop = false
    }
  },
  methods: {
    menuleft() {
      this.currentTabIndex = this.currentTabIndex - 1
    },
    menuright(index) {
      console.log(index)
      this.currentTabIndex = this.currentTabIndex + 1
    }
  }
}
</script>
<style lang="scss" scoped>
::v-deep .el-scrollbar__view {
  position: relative;
  .change {
    float: left;
    margin-top: 6px;
  }
}

::v-deep.el-menu--horizontal {
  display: inline-block;
  border-bottom: none;
  background-color: #000;
  width: 100%;
}

.scrollbar {
  background-color: #fff;
  .left {
    line-height: 55px;
    float: left;
    cursor: pointer;
  }
  .right {
    line-height: 55px;
    float: right;
    cursor: pointer;
  }
}
</style>

主要实现代码是