userApp.js

import Vue from 'vue';
import Vuex from 'vuex';
import VueRouter from 'vue-router';
import routes from './routes'; // user routes
import store from './store'; // user store

Vue.use(VueRouter);
Vue.use(Vuex);

// injecting the user routes to the vue router instance.
const router = new VueRouter({
  routes,
});

//creating a new vue instance
const userApp = new Vue({
  router,
  store,
});

//manually starting the mounting of unmounted vue instance.
userApp.$mount('#app');