javascript - 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，我想对其重新排序:

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

我需要的结果:

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

我尝试了很多方法，也一直在google上查找，但无法解决这个问题，欢迎任何指导

编辑:谢谢大家，Tai Le的解决方案非常完美，也感谢Marcelo Origoni也指出了我的错误，我在这里学到了很多东西，谢谢!

Answer 1

因为您没有初始化嵌套属性的值。这段代码可能不完全是你所期望的，但指出了你的问题是什么

   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);