Question

Geofire文档说Geofire在读取和写入数据时会返回承诺，但我似乎无法找到任何这方面的例子。我想知道如何在javascript中使用它来将函数附加到在完成geofire承诺时触发的侦听器的末尾。我的代码是：

var onKeyEnteredRegistration = this.geoQuery.on("key_entered", function(key, location, distance) {
    console.log(key + " entered query at " + location + " (" + distance + " km from center)");
    }).then(function(result){
          console.log("promise resolved with:" + result);
        }, function(error){
          console.error(error)
        });

但是这输出的错误是“未定义不是函数”。引用链式函数。有谁知道如何在Geofire中使用承诺？

由于

Answer 1

因此，get类上的set，remove和GeoFire函数仅返回promise。像这样：

geoFire.get("some_key").then(function(location) {
  if (location === null) {
    console.log("Provided key is not in GeoFire");
  }
  else {
    console.log("Provided key has a location of " + location);
  }
}, function(error) {
  console.log("Error: " + error);
});

但是，on函数返回一个GeoQuery，而on函数返回一个GeoCallbackRegistration，该cancel用于终止var onKeyEnteredRegistration = this.geoQuery.on("key_entered", function(key, location, distance) { console.log(key + " entered query at " + location + " (" + distance + " km from center)"); }); onKeyEnteredRegistration.cancel(); // the "key_entered" event will stop firing函数的查询（不返回任何内容。）

$(function(){
 //Initial code goes here
});

使用Geofire中的承诺

1 个答案: