访问未命名对象的属性（在对象内）答案

【问题标题】：Accessing properties of unnamed objects (within an object)访问未命名对象的属性（在对象内）
【发布时间】：2015-01-26 17:21:42
【问题描述】：

我正在使用 Javascript/JQuery 来使用 Google Web 服务，并且可以毫无问题地检索 JSON 结果，将它们存储在一个 var（名为 searchResults）中。在此示例中，我只是将要显示的所有信息从对象（address_components 的每个子对象中的 long_name 以及 lat & lng 值）添加到字符串 var (displayTxt)。

但是，结果中有许多未命名的对象，我找不到简单的方法来定位它们。我想使用标准的 object.property 语法，尽管如果没有命名对象（并且有多个），这是不可能的。我已经使用嵌入式 $.each 循环来遍历每个连续的对象，这个解决方案确实有效，但我认为它不是很整洁。所以我的问题是：有没有更好的方法来达到同样的结果？

$( "#displayBtn" ).click(function()
 {
    var displayTxt = "";
    if (searchResults.results)
        {

            $.each(searchResults.results, function (k,v)
                   {
                    displayTxt +=( "Result ID: " + k + "<br>");
                    $.each(v,function(a,b)
                           {
                            if(a=="address_components")
                                { 
                                $.each(b,function(c,d)
                                       {
                                        displayTxt += (d.long_name + "<br>")
                                        })
                                }
                            })
                    displayTxt+= "lat:" + v.geometry.location.lat +"<br>";
                    displayTxt+= "lng:" + v.geometry.location.lng +"<br><br>";
                   }
                  )

        };
     $('#resultsDisplay').html(displayTxt); 
});

这里是 searchResults 对象：

{
"results" : [
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Exeter",
           "short_name" : "Exeter",
           "types" : [ "administrative_area_level_3", "political" ]
        },
        {
           "long_name" : "Berks County",
           "short_name" : "Berks County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "Pennsylvania",
           "short_name" : "PA",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        }
     ],
     "formatted_address" : "Reading, PA, USA",
     "geometry" : {
        "bounds" : {
           "northeast" : {
              "lat" : 40.371134,
              "lng" : -75.890512
           },
           "southwest" : {
              "lat" : 40.296401,
              "lng" : -75.9598731
           }
        },
        "location" : {
           "lat" : 40.3356483,
           "lng" : -75.9268747
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 40.371134,
              "lng" : -75.890512
           },
           "southwest" : {
              "lat" : 40.296401,
              "lng" : -75.9598731
           }
        }
     },
     "types" : [ "locality", "political" ]
  },
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "postal_town" ]
        },
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "England",
           "short_name" : "England",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United Kingdom",
           "short_name" : "GB",
           "types" : [ "country", "political" ]
        }
     ],
     "formatted_address" : "Reading, Reading, Reading, UK",
     "geometry" : {
        "bounds" : {
           "northeast" : {
              "lat" : 51.4931339,
              "lng" : -0.9284944000000001
           },
           "southwest" : {
              "lat" : 51.4097795,
              "lng" : -1.0636011
           }
        },
        "location" : {
           "lat" : 51.4542645,
           "lng" : -0.9781303
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 51.4931339,
              "lng" : -0.9284944000000001
           },
           "southwest" : {
              "lat" : 51.4097795,
              "lng" : -1.0636011
           }
        }
     },
     "types" : [ "locality", "political" ]
  },
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Middlesex County",
           "short_name" : "Middlesex County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "Massachusetts",
           "short_name" : "MA",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        }
     ],
     "formatted_address" : "Reading, MA, USA",
     "geometry" : {
        "bounds" : {
           "northeast" : {
              "lat" : 42.566432,
              "lng" : -71.07103499999999
           },
           "southwest" : {
              "lat" : 42.5006449,
              "lng" : -71.1361789
           }
        },
        "location" : {
           "lat" : 42.5256563,
           "lng" : -71.0952891
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 42.566432,
              "lng" : -71.07103499999999
           },
           "southwest" : {
              "lat" : 42.5006449,
              "lng" : -71.1361789
           }
        }
     },
     "types" : [ "locality", "political" ]
  },
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Hamilton County",
           "short_name" : "Hamilton County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "Ohio",
           "short_name" : "OH",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        }
     ],
     "formatted_address" : "Reading, OH, USA",
     "geometry" : {
        "bounds" : {
           "northeast" : {
              "lat" : 39.240921,
              "lng" : -84.407549
           },
           "southwest" : {
              "lat" : 39.2038819,
              "lng" : -84.454735
           }
        },
        "location" : {
           "lat" : 39.2236694,
           "lng" : -84.44216410000001
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 39.240921,
              "lng" : -84.407549
           },
           "southwest" : {
              "lat" : 39.2038819,
              "lng" : -84.454735
           }
        }
     },
     "types" : [ "locality", "political" ]
  },
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Windsor County",
           "short_name" : "Windsor County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "Vermont",
           "short_name" : "VT",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        }
     ],
     "formatted_address" : "Reading, VT, USA",
     "geometry" : {
        "bounds" : {
           "northeast" : {
              "lat" : 43.561169,
              "lng" : -72.53007579999999
           },
           "southwest" : {
              "lat" : 43.4440849,
              "lng" : -72.66064299999999
           }
        },
        "location" : {
           "lat" : 43.494167,
           "lng" : -72.59638900000002
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 43.561169,
              "lng" : -72.53007579999999
           },
           "southwest" : {
              "lat" : 43.4440849,
              "lng" : -72.66064299999999
           }
        }
     },
     "types" : [ "locality", "political" ]
  },
  {
     "address_components" : [
        {
           "long_name" : "Reading",
           "short_name" : "Reading",
           "types" : [ "locality", "political" ]
        },
        {
           "long_name" : "Summit Lake",
           "short_name" : "Summit Lake",
           "types" : [ "administrative_area_level_3", "political" ]
        },
        {
           "long_name" : "Nobles County",
           "short_name" : "Nobles County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "Minnesota",
           "short_name" : "MN",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        },
        {
           "long_name" : "56165",
           "short_name" : "56165",
           "types" : [ "postal_code" ]
        }
     ],
     "formatted_address" : "Reading, MN 56165, USA",
     "geometry" : {
        "location" : {
           "lat" : 43.7035752,
           "lng" : -95.7130676
        },
        "location_type" : "APPROXIMATE",
        "viewport" : {
           "northeast" : {
              "lat" : 43.70492418029149,
              "lng" : -95.71171861970849
           },
           "southwest" : {
              "lat" : 43.70222621970849,
              "lng" : -95.71441658029151
           }
        }
     },
     "types" : [ "locality", "political" ]
  }
],
"status" : "OK"
}

【问题讨论】：

“未命名的对象”是什么意思？听起来您确实在谈论使用数组元素...
结果包含对象数组，因此您只能遍历这些数组。
事后看来，我不得不同意。 JavaScript 新手。

标签： javascript jquery

【解决方案1】：

看起来好像您有一个没有名称的对象数组（它们没有分配给变量，只是数组的一部分）。不过，您确实有几个不同的选项来迭代数组。

经典的迭代器是使用长度的for循环，如：

var data = [{value: 1}, {value: 2}, {value: 3}, {value: 4}, {value: 5}];

for (var i = 0; i < data.length; ++i) {
  console.log(data[i].value);
}

这将记录遇到的每个项目，并使用数组索引来访问它们。项目是什么并不重要，您只需更改数组中的逻辑即可。与$.each 一样，您可以嵌套这些循环（只需确保使用不同的变量）。

如果您可以访问一些新的 JS 功能，则forEach 方法已添加到数组中，您可以这样做：

var data = [{value: 1}, {value: 2}, {value: 3}, {value: 4}, {value: 5}];

data.forEach(function(it) {
  console.log(it.value);
});

这更像$.each，但它是内置在数组中的，并且在迭代 DOM 元素等时没有相同的语义。同样，您可以嵌套这些，但无需担心计数器。如果可用，这是推荐的方式。

无论哪种方式，一旦你有了项目（通过从数组中访问它），你就有了一个“名称”（它被分配给一个变量），你可以使用普通的对象访问语法来获取其中的属性对象。

如果您想将数据转换为新数组或将元素组合为单个返回值，您可以查看 map 或 reduce 之类的方法，这些方法现在可用于数组（以前来自 @ 等库） 987654323@ 和 lodash)。

【讨论】：

解释得很好，谢谢。我没有将诸如“结果”“address_components”之类的项目正确地视为数组，而是将其视为“内部带有对象的对象”，这引起了混乱。我要试试 results.forEach() 方法。