Vue3代码 

APP文件中写入js代码

1、首先，通过isMobile()函数判断用户的设备类型。该函数使用正则表达式匹配navigator.userAgent字符串，以确定用户是在移动设备上访问网页还是在桌面设备上访问网页

2、然后，在onMounted()钩子函数中，根据当前的路由路径来判断是否需要进行重定向。如果当前路径是根路径('/')或移动端首页路径('/mobile_index')，则会进一步检查设备类型。

3、如果是移动设备，则通过router.replace('/mobile_index')将路由重定向到移动端首页。如果是桌面设备，则通过router.replace('/')将路由重定向到桌面端首页。

<script setup lang="ts">
import { onMounted } from 'vue';
import { useRouter, useRoute } from 'vue-router'
const router = useRouter()
const route = useRoute()
const isMobile = () => {
  let flag = navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)
  return flag;
}

onMounted(() => {
  if (route.path === '/' || route.path === '/mobile_index') {
    if (_isMobile()) {
      router.replace('/mobile_index')
    } else {
      router.replace('/')
    }
  }
})

router中写法

import type { RouteRecordRaw } from 'vue-router'
export const staticRoutes: Array<RouteRecordRaw> = [
  // pc
  {
    path: '/',
    component: () => import('../views/pc_index.vue'),
    redirect: '/home',
    children: [
      {
        path: '/home',
        name: 'Home',
        component: () => import('../views/home/index.vue'),
        meta: {
          title: '首页',
          icon: 'ele-HomeFilled',
        },
      },
     
      // 公司产品
      {
        path: '/companyProducts',
        name: 'companyProducts',
        redirect: '/companyProducts/coalAR',
        children: [
          {
            path: '/companyProducts/coalAR',
            name: 'coalAR',
            component: () =>
              import('../views/companyProducts/coal/coalAR/index.vue'),
          }
          
        ],
      },
    
    ],
  },
  // 手机端首页
  {
    path: '/mobile_index',
    component: () => import('../views/mobile_index.vue'),
    redirect: '/mobileIndex',
    children: [
      {
        path: '/mobileIndex',
        name: 'mobileIndex',
        component: () => import('../views/mobile/mobileIndex.vue'),
        meta: {
          title: '首页',
          icon: 'ele-HomeFilled',
        }
      },
    
      // 公司产品
      {
        path: '/mobileProducts',
        name: 'mobileProducts',
        redirect: '/mobileProducts/coalAR',
        children: [
          {
            path: '/mobileProducts/coalAR',
            name: 'mobileCoalAR',
            component: () =>
              import('../views/mobile/mobileProducts/coal/coalAR/index.vue'),
          }
        ]
      }

    ]
  },
]

Vue2写法

在 App.vue 的 mounted 方法中对设置进行判断，如下:

//App.vue
mounted() {
    if (this._isMobile()) {
      alert("手机端");
      this.$router.replace('/m_index');
    } else {
      alert("pc端");
      this.$router.replace('/pc_index');
    }
  }，
methods:{
 isMobile = () => {
  let flag =     navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)
  return flag;
}
}

/在 router/index.js 中有两个页面。

//在 router/index.js 中有两个页面。
export default new Router({
  mode: 'history',
  routes: [
    {
      path: '',
      redirect: '/pc_index'
    },
    {
      path: "/pc_index", // pc端首页
      name: PcIndex,
      component: PcIndex
    },
    {
      path: '/m_index', // 手机端首页
      name: MIndex,
      component: MIndex
    }
  ]
});

参考vue2链接地址：【Vue】判断设备是移动端还是pc端_vue判断是pc端还是移动端-CSDN博客