vue watch怎样同时监听两个值的变化并执行方法？
```
watch:{
      city(cur,old){
          this.loadTop();
      },
      country(cur,old){
//        this.loadTop();
      },
    }
```
如上，我想在城市和国家都变化的时候执行刷新的方法，而不是单一执行刷新
用computed定义一个address对象吧，然后再去watch addres
```
data() {
  return {
    city: '',
    country: ''
  }
},
computed: {
  address() {
    const { city, country } = this
    return {
      city,
      country
    }
  }
},
watch: {
  address: {
    handler: function(val) {
      console.log('address change: ', val)
    },
    deep: true
  }
}

```
只的在computed里面调用也行，不过要使用$nextTick，不然值会是更新前的值。
```
data() {
  return {
    city: '',
    country: ''
  }
},
computed: {
  address() {
    const { city, country } = this
    this.$nextTick(() => {
      console.log(this.city, this.country, 3333)
    })
    return {
      city,
      country
    }
  }
},
```