Question

我想阅读我的JSON并计算分数和显示总数这不起作用，任何修改代码的建议。

HTML

<div> <p id="newme"> </p> </div>

JS

    var points = {"marks" : [
                                {"Subject" : csharp, "Score" : 5},
                                {"Subject" : csharp, "Score" : 7},
                                {"Subject" : Java, "Score" : 6},
                                {"Subject" : cpp, "Score" : 9 },
                                {"Subject" : Java, "Score" : 10},
                                {"Subject" : Java, "Score" : 4}
                            ]
                };
points = JSON.stringify(points);
var Java = "Java";
for (var i=0;i<points.marks.length;i++){
if(points.marks[i].Subject==Java){
    var totJava = totJava + points.marks[i].Score;
}
}
document.getElementById("newme").innerHTML= totJava;

I have tired this on Fiddle

Answer 1

你不能有这样的

"Subject" : csharp,  //ERROR

最好用双引号"csharp"

括起这些值

var points = {
    "marks": [{
        "Subject": "csharp",
            "Score": 5
    }, {
        "Subject": "csharp",
            "Score": 7
    }, {
        "Subject": "Java",
            "Score": 6
    }, {
        "Subject": "cpp",
            "Score": 9
    }, {
        "Subject": "Java",
            "Score": 10
    }, {
        "Subject": "Java",
            "Score": 4
    }]
};

//points = JSON.stringify(points);  //NO NEED TO PARSE THIS
var Java = "Java";
var totJava = 0; // declare globally with default 0 as value
for (var i = 0; i < points.marks.length; i++) {

    if (points.marks[i].Subject == Java) {
        totJava = totJava + points.marks[i].Score;
    }
}
document.getElementById("newme").innerHTML = totJava;

Answer 2

首先它不是一个有效的JSon简单的javascript对象其次，您应该提供默认总数

请参阅solution here

var Java = "Java";
var totJava = 0;
for (var i=0;i<points.marks.length;i++){
   if(points.marks[i].Subject==Java){
     totJava += parseInt(points.marks[i].Score,10);
   }
}
document.getElementById("newme").innerHTML= totJava;

Answer 3

这里有几点不对，请查看http://jsfiddle.net/XQymX/

更新的小提琴

json对象就像这样

var points = {"marks" : [{
                     "Subject" : "csharp",
                     "Score" : 5
                    },{
                     "Subject" : "csharp",
                     "Score" : 7
                    },{
                     "Subject" : "Java",
                     "Score" : 6
                    },{
                     "Subject" : "cpp",
                     "Score" : 9
                    },{
                     "Subject" : "Java",
                     "Score" : 10
                    },{
                     "Subject" : "Java",
                     "Score" : 4
                    }
                  ]
    };

并且无需执行此操作points = JSON.stringify(points);

如何阅读JSON的特定字段并进行计算和显示

3 个答案: