Lazy loading of vue-cli3 routes does not take effect

problem description

vue-cli3 project does not take effect according to the routing lazy loading written in document const Foo = () = > import (". / Foo.vue") . All routing components are loaded when
loads the home page.

there are also some center~city~food...js files

related codes

/ / Please paste the code text below (do not replace the code with pictures)
vue.config.js configuration

module.exports = {
  productionSourceMap: false,
  css: {
    extract: false,
    // css
    loaderOptions: {
      sass: {
        data: `@import "@/style/index.scss";`
      }
    }
  },
  devServer: {
    host: "0.0.0.0",
    port: 8000,
    proxy: "http://cangdu.org:8001"
  }
}

routing profile router.js

import Vue from "vue"
import Router from "vue-router"

Vue.use(Router)

const routes = [
  // home
  {
    path: "",
    redirect: "/home"
  },
  // 
  {
    name: "home",
    path: "/home",
    component: () => import(/* webpackChunkName: "home" */  `@/views/home/home.vue`)
  },
  // 
  {
    name: "city",
    path: "/city/:cityid",
    component: () => import(/* webpackChunkName: "city" */  `@/views/city/city.vue`)
  },
  // 
  {
    name: "msite",
    path: "/msite/",
    component: () => import(/* webpackChunkName: "msite" */ "./views/msite/msite.vue")
  },
  // 
  {
    name: "food",
    path: "/food/",
    component: () => import(/* webpackChunkName: "food" */ "@/views/food/food.vue")
  },
  // 
  {
    name: "search",
    path: "/search/",
    component: () => import(/* webpackChunkName: "search" */ "./views/search/search.vue")
  },
  // 
  {
    name: "order",
    path: "/order/",
    component: () => import(/* webpackChunkName: "order" */ "./views/order/order.vue")
  },
  // 
  {
    name: "center",
    path: "/center/",
    component: () => import(/* webpackChunkName: "center" */ "./views/center/center.vue")
  },
  // 
  {
    name: "login",
    path: "/login/",
    component: () => import(/* webpackChunkName: "login" */ "./views/login/login.vue")
  }
]

const router = new Router({
  mode: "history",
  base: process.env.BASE_URL,
  routes,
  scrollBehavior(to, from, savedPosition) {
    //  savedPosition  popstate ( / )
    if (savedPosition) {
      return savedPosition
    } else {
      if (from.meta.keepAlive) {
        from.meta.savedPosition = document.body.scrollTop
      }
      return { x: 0, y: to.meta.savedPosition || 0 }
    }
  }
})

export default router