problem.js

// router.js
import VueRouter from 'vue-router'

const Foo = { template: '<div>foo</div>' }
const Bar = { template: '<div>bar</div>' }

const routes = [
  { path: '/foo', component: Foo },
  { path: '/bar', component: Bar }
]

export default new VueRouter({
  routes
})

// main.js
import Vue from 'vue'
import App from './App.vue'
import VueRouter from 'vue-router'
import router from './router'

Vue.config.productionTip = false

Vue.use(VueRouter)

new Vue({
  router,
  render: h => h(App)
}).$mount('#app')

// App.vue
<template>
  <div id="app">
    <router-link to="/foo">Go to Foo</router-link>
    <router-link to="/bar">Go to Bar</router-link>
    <router-view/>
  </div>
</template>

<script>
export default {
  name: 'app',
}
</script>

<style>
#app {
  font-family: 'Avenir', Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
</style>

// vue.config.js
module.exports = {
  lintOnSave: true
}

// package.json
{
  "name": "photos",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve --open",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "vue": "^2.5.13",
    "vue-router": "^3.0.1"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "^3.0.0-alpha.6",
    "@vue/cli-plugin-eslint": "^3.0.0-alpha.6",
    "@vue/cli-service": "^3.0.0-alpha.6",
    "vue-template-compiler": "^2.5.13"
  },
  "babel": {
    "presets": [
      "@vue/app"
    ]
  },
  "eslintConfig": {
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ]
  },
  "postcss": {
    "plugins": {
      "autoprefixer": {}
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not ie <= 8"
  ]
}