javascript - 使用 for..in 循环访问 JSON 数据

Question

我刚刚学习如何从 JSON 文件中检索数据并充分利用它，我发现 for..in 循环很有用，但我知道我做的太多而无法获取值一个 JSON 文件。

这是我的 JSON - 它不必以这种方式构建。

var dollars = { "zipcodes": {
    "one": {
      "donors": {
          "donor_profile1": {
                   "name": "Doug Smith",
                   "address" : "123 main st",
                   "gifts":{
                    "gift0": {
                         "recipient":"Greg",
                         "amount": 45000,
                         "date":"7/1/2013"
                         },
                     "gift1":{
                        "recipient":"Greg",
                        "amount": 6000,
                        "date":"7/1/2013"
                        },
                        "gift2":{
                        "recipient":"Marty",
                        "amount": 2000,
                        "date":"7/1/2013"
                        }
                    }
                   },
            "donor_profile2": {
                        "name": "Bert Bernard",
                        "address" : "123 South st",
                        "gifts": {
                            "gift0": {
                            "recipient":"Greg",
                            "amount": 1200,
                            "date":"7/4/2013"
                              },
                            "gift1":{
                            "recipient":"Marty",
                            "amount": 400,
                            "date":"7/9/2013"
                            },
                            "gift2":{
                            "recipient":"Marty",
                            "amount": 510,
                            "date":"7/21/2013"
                            }
                        }
                    }
                }
            }

我想收集每个捐助者赠送的所有礼物并将它们加起来。我写这个程序是为了获得所有的礼物金额，但它们并没有被捐赠者分开。关于如何使这个清洁器有什么建议吗？

var info = dollars.zipcodes.one;


function buildSum(){
for (var key in info){

if (info.hasOwnProperty(key)) {
    var person = info[key];
    };
    for (prop in person) {
        if(person.hasOwnProperty(prop)){
            var name = person[prop].gifts;
        };
            for(value in name){
                if(name.hasOwnProperty(value)){
                    var money = name[value].amount;

                    };
                }

            }                       
    }

}
buildSum();

Answer 1

如评论部分所述，您可能应该在适当的地方使用数组。所以您的 JSON 数据可能如下所示:

var dollars = {
    "zipcodes": {
        "one": {
            "donors": [{
                "name": "Doug Smith",
                    "address": "123 main st",
                    "gifts": [{
                    "recipient": "Greg",
                        "amount": 45000,
                        "date": "7/1/2013"
                }, {
                    "recipient": "Greg",
                        "amount": 6000,
                        "date": "7/1/2013"
                }, {
                    "recipient": "Marty",
                        "amount": 2000,
                        "date": "7/1/2013"
                }]
            }, {
                "name": "Bert Bernard",
                    "address": "123 South st",
                    "gifts": [{
                    "recipient": "Greg",
                        "amount": 1200,
                        "date": "7/4/2013"
                }, {
                    "recipient": "Marty",
                        "amount": 400,
                        "date": "7/9/2013"
                }, {
                    "recipient": "Marty",
                        "amount": 510,
                        "date": "7/21/2013"
                }]
            }]
        }
    }
};

这使您能够使用 Array.prototype 的一些功能。就我而言，我使用 Array.map和 Array.reduce , 生成一个数组，其中包含每个捐赠者的捐赠总额:

//first map: turn the array of donors in an array of gift array
var res = dollars.zipcodes.one.donors.map(function (item) {

    //second map: turn each gift array in an array of amount
    return item.gifts.map(function (item) {
        return item.amount;

    //use reduce to sum up the amount in each array
    }).reduce(function (a, b) {
        return a + b;
    });
});

console.log(res); //[53000, 2110]

FIDDLE