javascript - 如何在回调函数中向正确的对象添加值？

Question

这个问题已经有答案了:

JavaScript closure inside loops – simple practical example (45 个回答)

已关闭 9 年前。

每次 while 循环运行时，下面的代码都会覆盖 var 存储。因此，当回调运行时，存储值通常是存储数组中的最后一项。

var stores = [];
stores.push({'address': "1 California Ave, San Francisco, CA"});
stores.push({'address': "16 California Ave, San Francisco, CA"});
stores.push({'address': "20 California Ave, San Francisco, CA"});
stores.push({'address': "30 California Ave, San Francisco, CA"});

var geocoder = new google.maps.Geocoder();

var i = 0;
while( i < stores.length){
  var store = stores[i];
  geocoder.geocode({'address':store.fullAddress}, function(data, status){
          store.latlng = data[0].geometry.location;
          }
        });
  i++;
};

如何将正确的纬度添加到正确的商店？

这也不起作用，因为 var i 也发生了变化。

var i = 0;
var storesObject = {}
while( i < stores.length){
  var store = stores[i];
  storesObject[i] = stores[i];
  geocoder.geocode({'address':store.fullAddress}, function(data, status){
          storesObject[i].latlng = data[0].geometry.location;
          }
        });
  i++;
};

如果我这样做，如何将结果与商店数组匹配？

var i = 0;
var results = [];
while( i < stores.length){
  var store = stores[i];
  geocoder.geocode({'address':store.fullAddress}, function(data, status){
          results.push(data[0].geometry.location);
          }
        });
  i++;
};

更新添加功能范围解决了我的问题:

var i = 0;
while( i < stores.length){
  (function(){
    var store = stores[i];
    geocoder.geocode({'address':store.fullAddress}, function(data, status){
          store.latlng = data[0].geometry.location;
          }
    });
  })();
  i++;
};

参见: GMaps JS Geocode: Using/Passing Variables With Asynchronous Geocode Function?

Answer 1

function geocodeAddress(store) {
   geocoder.geocode({'address':stores[store].address}, function(data, status){
     if (status == google.maps.GeocoderStatus.OK) {
       stores[store].latlng = data[0].geometry.location;
     } else {
         alert("Geocode failed: " + status);
     }
   });
}
var stores = [];
stores.push({'address': "1 California Ave, San Francisco, CA"});
stores.push({'address': "16 California Ave, San Francisco, CA"});
stores.push({'address': "20 California Ave, San Francisco, CA"});
stores.push({'address': "30 California Ave, San Francisco, CA"});

var geocoder = new google.maps.Geocoder();

var i = 0;
while( i < stores.length){
  geocodeAddress(i);
  i++;
};