REST调用中以JSON形式返回的数据出错！

(如果我使用的语言有点不正确，请原谅我—我随时可以根据需要进行纠正......)

有几篇关于从返回对象兄弟姐妹的JSON数据中获取数据的帖子，但我在将该信息应用于我的情况时遇到了困难：

我有一组对象从REST调用中以JSON的形式返回，对于每个具有特定键节点的对象：值，我需要提取特定密钥的兄弟节点的数值。例如：对于下面的对象列表，我需要将匹配“desc”的每个对象的“file_size”中的数字相加，并将其返回到页面上的匹配输入值。

{"ResultSet":{

  Result":[

    {
        "file_size":"722694",
        "desc":"description1",
        "format":"GIF"
    },

    {
        "file_size":"19754932",
        "desc":"description1",
        "format":"JPEG"
    },

    {
        "file_size":"778174",
        "desc":"description2",
        "format":"GIF"
    },

    {
        "file_size":"244569996",
        "desc":"description1",
        "format":"PNG"
    },

    {
        "file_size":"466918",
        "desc":"description2",
        "format":"TIFF"
    }

  ]

}}

That's an array embedded in an object, so

data.ResultSet.Result[2].file_size

would give you 778174

var sum = {}, result = ResultSet.Result

// Initialize Sum Storage
for(var i = 0; i < result.length; i++) {
  sum[result[i].desc] = 0; 
}

// Sum the matching file size
for(var i = 0; i < result.length; i++) {
  sum[result[i].desc] += parseInt(result[i]["file_size"]
}

After executing above code, you will have a JSON named sum like this

sum = {
  "description1": 20477629,
  "description2": 1246092
};

An iterate like below should do the job,

var result =  data.ResultSet.Result;
var stat = {};
for (var i = 0; i < result.length; i++) {    
    if (stat.hasOwnProperty(result[i].cat_desc)) {       
        if (result[i].hasOwnProperty('file_size')) {
        stat[result[i].cat_desc] += parseInt(result[i].file_size, 10);   
        }
    } else {
        stat[result[i].cat_desc] = parseInt(result[i].file_size, 10);
    }   
}

DEMO: http://jsfiddle.net/HtrLu/1/

You can use the following function:

function findSum(description, array) {
    var i = 0;
    var sum = 0;

    for(i = 0; i < array.length; i++) {
        if(array[i]["desc"] == description && array[i].hasOwnProperty("file_size")) {
            sum += parseInt(array[i]["file_size"], 10);
        }
    }

    alert(sum);
}

And call it like this:

findSum("description1", ResultSet.Result);

To display an alert with the summation of all "description1" file sizes.

A working JSFiddle is here: http://jsfiddle.net/Q9n2U/.

In response to your updates and comments, here is some new code that creates some divs with the summations for all descriptions. I took out the hasOwnProperty code because you changed your data set, but note that if you have objects in the data array without the file_size property, you must use hasOwnProperty to check for it. You should be able to adjust this for your jQuery .each fairly easily.

var data = {};
var array = ResultSet.Result;

var i = 0;
var currentDesc, currentSize;
var sizeDiv;
var sumItem;

//Sum the sizes for each description
for(i = 0; i < array.length; i++) {
    currentDesc = array[i]["desc"];
    currentSize = parseInt(array[i]["file_size"], 10);

    data[currentDesc] =
        typeof data[currentDesc] === "undefined"
        ? currentSize
        : data[currentDesc] + currentSize;
}

//Print the summations to divs on the page
for(sumItem in data) {
    if(data.hasOwnProperty(sumItem)) {
        sizeDiv = document.createElement("div");
        sizeDiv.innerHTML = sumItem + ": " + data[sumItem].toString();
        document.body.appendChild(sizeDiv);
    }
}

A working JSFiddle is here: http://jsfiddle.net/DxCLu/.