Question

我已经想过如何遍历以下here的JSON：

{"dummmysetsJSONArr":[{"entryID":"1","distance":"100","calories":"50"},{"entryID":"2","distance":"200","calories":"100"},{"entryID":"3","distance":"300","calories":"150"},{"entryID":"4","distance":"400","calories":"200"},{"entryID":"5","distance":"500","calories":"250"},{"entryID":"6","distance":"600","calories":"300"}],"success":1}

这是我如何做到的：

    for (var key in obj) {
        if (obj.hasOwnProperty(key)) {
            myLogger(jsonarray[key].entryID + " - " + jsonarray[key].distance + " - " + jsonarray[key].calories);
        }
    }

但是JSON在for循环中检查失败了。

我的JSON数据有什么问题？

我的目标是使用上面的for循环将数据添加到google.visualization.DataTable（），如下所示：

        data = new google.visualization.DataTable();
        data.addColumn('number', 'distance');
        data.addColumn('number', 'calories');

        for (var key in obj) {
            if (obj.hasOwnProperty(key)) {

                //data.addRow(jsonarray[key].distance);
                //data.addRow(jsonarray[key].calories);
            }
        }

Answer 1

如果您知道哪个属性包含您需要的集合（working example - jsbin）：

var obj = {"dummmysetsJSONArr":[{"entryID":"1","distance":"100","calories":"50"},{"entryID":"2","distance":"200","calories":"100"},{"entryID":"3","distance":"300","calories":"150"},{"entryID":"4","distance":"400","calories":"200"},{"entryID":"5","distance":"500","calories":"250"},{"entryID":"6","distance":"600","calories":"300"}],"success":1};


  for (var key in obj.dummmysetsJSONArr) {
            if (obj.dummmysetsJSONArr.hasOwnProperty(key)) {
              document.write(obj.dummmysetsJSONArr[key].distance + " " + obj.dummmysetsJSONArr[key].calories);              
              document.write("<br/>");
            }
        }

在其他情况下，最好的方法是找到所有具有entryId，distance和caloreis属性的对象，因为你的json可能有更多数组（我不知道这是动态json还是什么）

Answer 2

看起来您需要对键/值进行多次迭代。第一次迭代将为您提供键'dummmysetsJSONArr'和数组作为值。

然后你想迭代数组，每个键都是索引，值就是对象。

对值的下一次迭代将为您提供对象的属性名称和值。

Answer 3

该物业＆＃34; dummmysetsJSONArr＆＃34;不是一个对象而是一个数组，所以你可以这样做：

var myObj = {"dummmysetsJSONArr":[{"entryID":"1","distance":"100","calories":"50"},{"entryID":"2","distance":"200","calories":"100"},{"entryID":"3","distance":"300","calories":"150"},{"entryID":"4","distance":"400","calories":"200"},{"entryID":"5","distance":"500","calories":"250"},{"entryID":"6","distance":"600","calories":"300"}],"success":1}
var obj = myObj.dummmysetsJSONArr; //this is an array not an object
var str = "";
for (var i=0;i< obj.length;i++) {     
    str += obj[i].entryID + " - " + obj[i].distance + " - " + obj[i].calories+"<br>";
}

但是，JavaScript中的数组只是具有数字键的对象，因此您可以这样做：

var obj = myObj.dummmysetsJSONArr; //this is an array not an object
var str = "";
 for (key in obj) {     
            str += obj[key].entryID + " - " + obj[key].distance + " - " + obj[key].calories+"<br>";
    }

检查hasOwnProperty没有多大意义，因为你的JSON对象只是一个普通的对象而且每个属性都是它自己的属性

JSON - 为什么hasOwnProperty（key）返回false

3 个答案: