在javascript中将一个简单的java对象重新排序为3级对象

Question

我有以下包含对象的示例对象，我想重新排序它：

var thisarray = {
    0 : { topic: "devices/one/humid/value", message: "1"},
    1 : { topic: "devices/one/humid/unit", message: "%"},
    2 : { topic: "devices/one/temp/value", message: "2"},
    3 : { topic: "devices/one/temp/unit", message: "c"},
    4 : { topic: "devices/two/humid/value", message: "1"},
    5 : { topic: "devices/two/humid/unit", message: "%"},
    6 : { topic: "devices/two/temp/value", message: "2"},
    7 : { topic: "devices/two/temp/unit", message: "c"},
};
var arr = { };

for (var key in thisarray) {
    // skip loop if the property is from prototype
    if (!thisarray.hasOwnProperty(key)) continue;

    var obj = thisarray[key];
    var devicename = "";
    var variablename = "";
    var variableprop = "";

    for (var prop in obj) {
        // skip loop if the property is from prototype
        if(!obj.hasOwnProperty(prop)) continue;

        if(prop=="topic") {
            var localstrings = obj[prop].split("/");
            devicename = localstrings[1];
            variablename = localstrings[2];
            variableprop = localstrings[3];
        } else if(prop=="message") {
            //this line throws an error
            arr[devicename][variablename][variableprop]=obj[prop];
        }
    }  
}
console.log(arr);

这会引发错误

TypeError: Cannot read property 'humid' of undefined

结果我需要什么：

arr = {
    one : {
        humid : { value: 1 , unit : '%'},
        temp  : { value: 2 , unit : 'c'}
    },
    two : {
        humid : { value: 1 , unit : '%'},
        temp  : { value: 2 , unit : 'c'}
    }
}

我一直在尝试很多方法，我一直在寻找谷歌，但无法解决这个问题，欢迎任何指导

编辑：谢谢大家，泰乐的解决方案完美无缺，也感谢Marcelo Origoni指出我的错误，我在这里学到了很多，谢谢！

Answer 1

因为你没有为nest属性初始化值。此代码可能不完全符合您的预期，但指出您的问题是什么

   var thisarray = {
    0 : { topic: "devices/one/humid/value", message: "1"},
    1 : { topic: "devices/one/humid/unit", message: "%"},
    2 : { topic: "devices/one/temp/value", message: "2"},
    3 : { topic: "devices/one/temp/unit", message: "c"},
    4 : { topic: "devices/two/humid/value", message: "1"},
    5 : { topic: "devices/two/humid/unit", message: "%"},
    6 : { topic: "devices/two/temp/value", message: "2"},
    7 : { topic: "devices/two/temp/unit", message: "c"},
   };
  var arr = { };

  for (var key in thisarray) {
     // skip loop if the property is from prototype
    if (!thisarray.hasOwnProperty(key)) continue;

  var obj = thisarray[key];

  var devicename = "";
  var variablename = "";
  var variableprop = "";

  for (var prop in obj) {
      // skip loop if the property is from prototype
      if(!obj.hasOwnProperty(prop)) continue;


      if(prop=="topic") {
                var localstrings = obj[prop].split("/");
                devicename = localstrings[1];
                variablename = localstrings[2];
                variableprop = localstrings[3];
      } else if(prop=="message") {
          // Init value as empty object if it is undefined
          arr[devicename] = arr[devicename] || {};
          arr[devicename][variablename] = arr[devicename][variablename] || {};
          arr[devicename][variablename][variableprop]=obj[prop];
      }
  }  
}
console.log(arr);

Answer 2

错误很明显，arr[devicename]没有定义，你应该这样做：

arr[devicename] = {};
arr[devicename][variablename]  = {};
arr[devicename][variablename][variableprop]=obj[prop];

那一个，你将devicename和variablename定义为空对象，你可以创建和修改它的属性