从firebase查看http.get（）查询（通过vue-resource）的进度

Question

this.$http.get('cities_&_stops/' + this.search_city_name[0].toUpperCase() + '.json' )
    .then(response => {
      this.cities_array = [];
      return response.json();
    })
    .then(cities => {
      //console.log("cities from db -> "+cities);
      for(let city in cities){
        this.city_object = {
          name :  cities[city].toUpperCase(),
          class : ''
        }
        //console.log("pushing in array -> " + this.city_object.name);
        this.cities_array.push(this.city_object);
        //console.log("in city array -> " + this.city_object.name);
      }
      //console.log("what is in city array? -> " + this.cities_array);
      this.search_feature();
    })

这是我通过firebase数据库中的http.get（）方法（使用vue-resouce）查询的。

如何在控制台中查看我的进度（％）。