Question

我想创建一个类似下面代码的对象：

MyObject ={
 "United Kingdom":{
    "primary":{ 

    },
    "secondary":{

    },
    "service":{

    },  
},

"France":{
    "primary":{


    },
    "secondary":{

    },
    "service":{

    },  
},

我想要做的是自动从数组生成对象，所以我有两个数组：

CountryList = ["United Kingdom", "France"]

MarketList = ["primary", "secondary", "service"]

我是通过for循环

来完成的

for (var i = 0; i < CountryList.length; i++) {
  for(var p = 0; p < MarketList.length; p++)
      MyObject[CountryList[i]][MarketList[p]] = self;
}

但是我收到了一个错误：

Cannot set property 'primary' of undefined

关于我错在哪里的任何想法？它在循环遍历国家/地区列表时运行正常，但是当我想在其中嵌入“市场”对象时，我遇到了问题。

谢谢！

Answer 1

在为其分配属性之前需要一个对象

myObject[countryList[i]] = {};

提示，大写字母和后面的小写字母表示可以用作构造函数的类或函数。

var myObject = {},
    countryList = ["United Kingdom", "France"],
    marketList = ["primary", "secondary", "service"],
    i, p;

for (var i = 0; i < countryList.length; i++) {
    myObject[countryList[i]] = {};
    for (p = 0; p < marketList.length; p++) {
        myObject[countryList[i]][marketList[p]] = {};
    }
}

console.log(myObject);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

您需要添加一个条件来测试MyObject[]是否未定义。

if (MyObject[CountryList[i]]) {
      MyObject[CountryList[i]][MarketList[p]] = self;      
}

我认为，你提到的错误将不复存在。

Answer 3

使用ES6，您可以使用对象解构来获取两个变量，并使用reduce()来创建该对象。

＆＃13;

var MyObject ={"United Kingdom":{"primary":{},"secondary":{},"service":{}},"France":{"primary":{},"secondary":{},"service":{}}}

var result = Object.keys(MyObject).reduce(function(r, e) {
  if (!r.CountryList || !r.MarketList) r.CountryList = [], r.MarketList = []
  r.MarketList = [...new Set(r.MarketList.concat(Object.keys(MyObject[e])))]
  r.CountryList.push(e)
  return r
}, {})

var {MarketList,CountryList} = result
console.log(MarketList)
console.log(CountryList)

＆＃13;

组合两个数组以形成嵌套的javascript对象

3 个答案: