javascript 对象属性未定义，但它在那里答案

【问题标题】：javascript Object property undefined, but it's therejavascript 对象属性未定义，但它在那里
【发布时间】：2017-01-05 12:02:12
【问题描述】：

我有一个如下所示的 json 文件：

 { 
   "results": {
    "name1": {
        "printouts": {
            "property1": [{
                    "someName": "someText",
                    "someName2": "someURL",
                    "someName3": integer,
                    "someName4": boolean
                }
            ],
            "property2": [
                "someText"
            ],
            "property3": [
                "someText"
            ],
            "property4": [
                "someText"
            ],
            "property5": [
                "someText"
            ],
            "property6": [
                "someText"
            ]
        },
        "someName": "someText",
        "someName2": "someURL",
        "someName3": integer,
        "someName4": boolean
    },
    "name2": {
        "printouts": {
            "property1": [{
                    "fulltext": "someText",
                    "fullurl": "someURL",
                    "namespace": integer,
                    "exists": boolean
                }
            ],
            "property2": [
                "someText"
            ],
            "property3": [
                "someText"
            ],
            "property4": [
                "someText"
            ],
            "property5": [
                "someText"
            ],
            "property6": [
                "someText"
            ]
        },
        "someName": "someText",
        "someName2": "someURL",
        "someName3": integer,
        "someName4": boolean
    },
 ......
}

我想要的是访问printouts 中每个对象的property6。到目前为止我做了什么：

 for (i in results) {
        if (someOtherArray.length < 1) {
            someOtherArray.push(i.printouts.property6.toString());
        }

但这让我出错：无法读取未定义的属性 property6。我做错了什么？

有什么想法吗？谢谢。

【问题讨论】：

可能是i.name.printouts.property6.toString()
results 应该是一个数组，而不是一个对象，因为它具有双重名称属性。
看起来你在someText 之后还有一个额外的" ► "property5": [someText"],
i 将在字符串中保存键名。您必须使用results[i] 来获取对象
@dnks23，但你有两个 name 里面的钥匙。

标签： javascript arrays object properties undefined

【解决方案1】：

基本上你对属性的访问权限是错误的

i.printouts.property6

它必须是一个带有property accessor 的对象，变量的括号表示法。

data.results[i].printouts.property6
//^^^^^^^^^^^^^

然后你可以遍历键并选择你想要的属性。

var data = { results: { name1: { printouts: { property1: [{ someName: "someText", someName2: "someURL", someName3: 33, someName4: false }], property2: ["someText"], property3: ["someText"], property4: ["someText"], property5: ["someText"], property6: ["someText"] }, someName: "someText", someName2: "someURL", someName3: 37, someName4: true }, name2: { printouts: { property1: [{ fulltext: "someText", fullurl: "someURL", namespace: 35, "exists": true }], property2: ["someText"], property3: ["someText"], property4: ["someText"], property5: ["someText"], property6: ["someText"] }, someName: "someText", someName2: "someURL", someName3: 34, someName4: false } } };

Object.keys(data.results).forEach(function (k) {
    console.log(data.results[k].printouts.property6);
});

【讨论】：