javascript - 如何从 json 中检索这些值？

Question

我正在尝试通过 jquery ajax 从 google map 检索某个位置的纬度和经度。

这是我的 JavaScript 代码:

    var lat;
    var lng;

    function setCordinates(address)
    {
        var ret = false;
        data = "address="+address;
        $.ajax({
            type: "GET",
            url: "https://maps.googleapis.com/maps/api/geocode/json",
            data: data,
            cache: false,
            dataType: 'json',
            success: function(json_data)
            {
                lat = json_data.results.geometry.location.lat;
                lng = json_data.results.geometry.location.lng;
                ret = true;
            },
            error: function()
            { 
                alert("There was an error!");
            }
        });
        return ret;
    }

当我从控制台预览响应正文时，我得到的 json 数据返回为:

{
    "results" : [ 
        { 
            "address_components" : [ 
                { 
                    "long_name" : "Uyo", 
                    "short_name" : "Uyo", 
                    "types" : [ "locality", "political" ] 
                }, 
                { 
                    "long_name" : "Akwa Ibom", 
                    "short_name" : "Akwa Ibom", 
                    "types" : [ "administrative_area_level_1", "political" ] 
                }, 
                { 
                    "long_name" : "Nigeria", 
                    "short_name" : "NG", 
                    "types" : [ "country", "political" ] 
                } 
            ], 
            "formatted_address" : "Uyo, Nigeria", 
            "geometry" : 
            { 
                "bounds" : 
                { 
                    "northeast" : 
                    { 
                        "lat" : 5.0906023, 
                        "lng" : 8.0030251 
                    }, 
                    "southwest" : 
                    { 
                        "lat" : 4.9681658, 
                        "lng" : 7.8638077 
                    } 
                }, 
                "location" : 
                { 
                    "lat" : 5.0377396, 
                    "lng" : 7.9127945 
                }, 
                "location_type" : "APPROXIMATE", 
                "viewport" : 
                { 
                    "northeast" : 
                    { 
                        "lat" : 5.0906023, 
                        "lng" : 8.0030251 
                    }, 
                    "southwest" : 
                    { 
                        "lat" : 4.9681658, 
                        "lng" : 7.8638077 
                    } 
                } 
            }, 
            "partial_match" : true, 
            "types" : [ "locality", "political" ] 
        } 
    ], 
    "status" : "OK" 
} 

我试图从位置获取纬度和经度的值，但出现错误:

TypeError: json_data.results.geometry is undefined

我看过this post , this post , this post , this post和 this post但我真的不知道该怎么办。它们看起来都毫无关联。请帮助我对 json 还很陌生。谢谢。

Answer 1

这个怎么样:

lat = json_data.results[0].geometry.location.lat;
lng = json_data.results[0].geometry.location.lng;