Set as follows in router.js

import Vue from 'vue'
import Router from 'vue-router'
Vue.use(Router)

const router = new Router({
  routes: [{
      path: '/login',
      component: Login,
      meta: { title: '登录' }
    }, {
      path: '/register',
      component: Register,
      meta: { title: '注册' }
    }
  ]
})
// 全局配置
router.beforeEach((to, from, next) => {
  // Change doc title
  document.title = to.meta.title || 'Unknow title'
  document.querySelector('meta[name="keywords"]').setAttribute('content', 'keywords')
  document.querySelector('meta[name="description"]').setAttribute('content', 'description')
})

The basic tags of the entry file can be manipulated
You can operate the DOM in Router
router.beforeEach((to, from, next) => {
//Manipulate DOM here
// ...
/* console. log(to);
console.log(from);*/
next();
})