main.js

// The Vue build version to load with the `import` command
// (runtime-only or standalone) has been set in webpack.base.conf with an alias.
import Vue from 'vue'
import App from './App'
import router from './router'

import Vuex from 'vuex'
import VueSocketio from 'vue-socket.io'

import counterModule from './modules/counterModule'

Vue.use(Vuex)

Vue.config.productionTip = false

const store = new Vuex.Store({
  state: {
    io: {}//rootState.io
  },
  mutations: {
    setSocket: (state, socket) => {
      state.io = socket 
      console.log('socket connected')
    }
  },
  modules: {
    counterModule
  }
})

Vue.use(VueSocketio, 'http://localhost:5000', store)

new Vue({
  el: '#app',
  router,
  store,
  //en cada carga, definimos un socket para este cliente
  beforeCreate () {
    store.commit('setSocket', this.$socket)
  },
  template: '<App/>',
  components: { App }
})