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How do I return a variable from Google Maps JavaScript geocoder callback? (5 answers)

Closed 7 years ago.

我的职能如下:

function mainFunction() {
      function subFunction() {
            var str = "foo";
            return str;
      }
}

var test = mainFunction();
alert(test);

我的逻辑是,这种警示应当返回 f,而是重新界定。我做了什么错误?

www.un.org/Depts/DGACM/index_spanish.htm 这里是我的实际守则(它具有与“谷歌”普朗西语进行逆向居住的功能)

function reverseGeocode(latitude,longitude){
    var address = "";
    var country = "";
    var countrycode = "";
    var locality = "";

    var geocoder = new GClientGeocoder();
    var latlng = new GLatLng(latitude, longitude);

     return geocoder.getLocations(latlng, function(addresses) {
     address = addresses.Placemark[0].address;
     country = addresses.Placemark[0].AddressDetails.Country.CountryName;
     countrycode = addresses.Placemark[0].AddressDetails.Country.CountryNameCode;
     locality = addresses.Placemark[0].AddressDetails.Country.AdministrativeArea.SubAdministrativeArea.Locality.LocalityName;
     return country;
    });   
   }

Answer 1

你们必须要求一种功能,才能归还任何东西。

function mainFunction() {
      function subFunction() {
            var str = "foo";
            return str;
      }
      return subFunction();
}

var test = mainFunction();
alert(test);

或:

function mainFunction() {
      function subFunction() {
            var str = "foo";
            return str;
      }
      return subFunction;
}

var test = mainFunction();
alert( test() );

页: 1 返回应在主要职能之外进行。退约在<条码>中被称作“植被/代码”方法,因此,其返回价值在你的主要职能中不会丧失。

function reverseGeocode(latitude,longitude){
    var address = "";
    var country = "";
    var countrycode = "";
    var locality = "";

    var geocoder = new GClientGeocoder();
    var latlng = new GLatLng(latitude, longitude);

    geocoder.getLocations(latlng, function(addresses) {
     address = addresses.Placemark[0].address;
     country = addresses.Placemark[0].AddressDetails.Country.CountryName;
     countrycode = addresses.Placemark[0].AddressDetails.Country.CountryNameCode;
     locality = addresses.Placemark[0].AddressDetails.Country.AdministrativeArea.SubAdministrativeArea.Locality.LocalityName;
    });   
    return country
   }

Answer 2

权利。在获得数据之前,你通过接听电机获得电击功能,因此,在数据确定之前返回“国家”就没有帮助你。

你们需要这样做的方式是让你转往地球科学公司。确实,如果你想要按回归的价值观做些什么,就会感到担心。

与此类似:

function reverseGeocode(latitude,longitude){
  var geocoder = new GClientGeocoder();
  var latlng = new GLatLng(latitude, longitude);

  geocoder.getLocations(latlng, function(addresses) {
    var address = addresses.Placemark[0].address;
    var country = addresses.Placemark[0].AddressDetails.Country.CountryName;
    var countrycode = addresses.Placemark[0].AddressDetails.Country.CountryNameCode;
    var locality = addresses.Placemark[0].AddressDetails.Country.AdministrativeArea.SubAdministrativeArea.Locality.LocalityName;
    do_something_with_address(address, country, countrycode, locality);
  });   
}

function do_something_with_address(address, country, countrycode, locality) {
  if (country==="USA") {
     alert("USA A-OK!"); // or whatever
  }
}

如果你在找到地点时可能想做不同的事情,那么把这一功能作为另一个参数来逆转。 Geocode:

function reverseGeocode(latitude,longitude, callback){
  // Function contents the same as above, then
  callback(address, country, countrycode, locality);
}
reverseGeocode(latitude, longitude, do_something_with_address);

如果看看上去一点迷惑的话,那么你就可以看像杜霍的有色特征这样的东西,这使职能之间的链条变得更清楚。

Answer 3

仅是FYI, Geocoder, 如此,被接受的答案是同步的,而逻辑上确实如此。我更希望有一个外部目标,作为你的更新者。

var updater = {};

function geoCodeCity(goocoord) { 
    var geocoder = new google.maps.Geocoder();
    geocoder.geocode({
         latLng : goocoord
    }, function(results, status) {
        if (status == google.maps.GeocoderStatus.OK) {
            updater.currentLocation = results[1].formatted_address;
        } else {
            if (status == "ERROR") { 
                    console.log(status);
                }
        }
    });
};

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