store.js

import Vue from 'vue'
import Vuex from 'vuex'

import notification from './notifications/index'
import toast from './toasts/index'

Vue.use(Vuex)

const debug = process.env.NODE_ENV !== 'production'

const store = new Vuex.Store({
  strict: debug,
  modules: {
    notification,
    toast
  }
})

if (module.hot) {
  module.hot.accept([
    './notifications/index',
    './toasts/index'
  ], () => {
    store.hotUpdate({
      modules: {
        notification: require('./notifications/index').default,
        toast: require('./toasts/index').default
      }
    })
  })
}

export default store

toast-mutation-types.js

export const INIT_QUEUE = 'INIT_QUEUE'
export const DISPLAY = 'DISPLAY'
export const UPDATE_FLAG = 'UPDATE_FLAG'

toast-mutations.js

import * as types from './toast-mutation-types'

export default {
  [types.INIT_QUEUE] (state, size) {
    state.init = true
    state._max_toasts = size
    state.free = size

    for (let i = 0; i < size; ++i) {
      state.flags[i] = null
    }
  },

  [types.DISPLAY] (state, { id, notification }) {
    let i = state.flags.findIndex(elem => (elem === null))

    if (i !== -1) {
      state.flags[i] = {id, notification}
      state.free -= 1
    }
  },

  [types.UPDATE_FLAG] (state, { index, val }) {
    state.flags[index] = val

    if (val === null) state.free += 1
  }
}

toastmanager.js

import { mapGetters } from 'vuex'
import Toast from './toast/Toast'
import { DISPLAY } from 'store/toasts/toast-mutation-types'

const MAX_NOTICES = 5

export default {
  name: 'toast-manager',
  components: {
    Toast
  },
  watch: {
    isEmpty (empty) {
      if (!empty && this.$store.getters['toast/canDisplay']) {
        this.$store.dispatch('notification/pop_back')
          .then(pair => { this.$store.commit(DISPLAY, pair) }) // <-- вот тут
      }
    },

    canDisplay (able) {
      if (able && !this.$store.getters['notification/isEmpty']) {
        this.$store.dispatch('notification/pop_back')
          .then(pair => { this.$store.commit(DISPLAY, pair) }) // <-- вот тут
      }
    }
  },
  created () {
    this.$store.dispatch('toast/init', MAX_NOTICES)
  },

  computed: {
    ...mapGetters({
      isEmpty: 'notification/isEmpty',
      canDisplay: 'toast/canDisplay',
      toastStackSize: 'toast/toastStackSize'
    })
  }
}