Vuex状态监听mapState与普通的局部计算属性混合使用

mapState如果和普通的局部计算属性混合使用，使用对象展开运算符(…)

data () {
  return {
    order: {
      orderId: '',
      amount: 0.0
    }
  }
},
computed: {
  amount () {
    return this.order.amount
  },
  ...mapState({
    order_create_watcher: state => state.order.order_create
    order_confirm_watcher: state => state.order.order_confirm
  })
},
watch: {
  amount: 'amountWatcher',
  order_create_watcher: {
    handler: 'orderCreateWatcher',
    deep: true
  },
  order_confirm_watcher: {
    handler: 'orderConfirmWatcher',
    deep: true
  }
},
methods: {
  amountWatcher (val, oldVal) {
    ...
  },
  orderCreateWatcher (val, oldVal) {
    ...
  },
  orderConfirmWatcher (val, oldVal) {
    ...
  }
}