App.vue

<script>
  import Nav from './components/Nav.vue'
  import store from './vuex/store'

  export default {
    name: 'App',

    store,

    data() {
      return {
        // note: changing this line won't causes changes
        // with hot-reload because the reloaded component
        // preserves its current state and we are modifying
        // its initial state.
      }
    },

    components: {
      'cart-nav': Nav
    }
  }
</script>
<template>
  <div id="app">
    <cart-nav></cart-nav>
    <!-- 路由外链 -->
    <router-view></router-view>
  </div>
</template>