logo标签列表

使用动态属性名称访问嵌套属性

javascriptarraysjson
4

我有一个从这个JSON生成的对象：

{
    "data":  {
        "Meta Data": {
            "1. Information": "Monthly Prices (open, high, low, close) and Volumes",
            "2. Symbol": "MSFT",
            "3. Last Refreshed": "2017-08-18",
            "4. Time Zone": "US/Eastern"
        },
        "Monthly Time Series": {
            "2017-08-18": {
                "1. open": "73.1000",
                "2. high": "74.1000",
                "3. low": "71.2800",
                "4. close": "72.4900",
                "5. volume": "285933387"
            },
            "2017-07-31": {
                "1. open": "69.3300",
                "2. high": "74.4200",
                "3. low": "68.0200",
                "4. close": "72.7000",
                "5. volume": "451248934"
            }
        }
    }
}

使用Object.keys()，我能够获取到键"Monthly time series"，但是如何访问它内部的键呢？我想在"Monthly time series"键中运行一个for循环，遍历其中的键。我该怎么做呢？
在执行此操作后，@Hitmands 中的 Json 出现意外的 'o' 标记。 - Aayushi
你有一个JSON或JavaScript对象吗？ - Hitmands
1
你为什么要使用 Object.keys() 来访问一个非随机属性，比如 "Monthly Time Series"？ - Andreas
你还有什么建议吗？@Andreas - Aayushi
2
var monthlyTimeSeries = object["data"]["Monthly Time Series"]; - Andreas
显示剩余3条评论
2个回答
2
您可以使用Object.keys()来获取键的数组，但我建议您使用Array.prototype.forEach()迭代键的数组，而不是使用for...loop。

代码:

const obj = {"data": {"Meta Data": {"1. Information": "Monthly Prices (open, high, low, close) and Volumes","2. Symbol": "MSFT","3. Last Refreshed": "2017-08-18","4. Time Zone": "US/Eastern"},"Monthly Time Series": {"2017-08-18": {"1. open": "73.1000","2. high": "74.1000","3. low": "71.2800","4. close": "72.4900","5. volume": "285933387"},"2017-07-31": {"1. open": "69.3300","2. high": "74.4200","3. low": "68.0200","4. close": "72.7000","5. volume": "451248934"}}}};

Object
  .keys(obj.data['Monthly Time Series'])
  .forEach(function (k) {
    console.log(obj.data['Monthly Time Series'][k]['1. open']);
  });

1
如何访问“月度时间序列”中的“1.open”值？如果我重复上述方法，它会显示未定义！ - Aayushi
1

你可以通过Object.keys函数来访问键，就像你现在正在访问它们一样。

var data = JSON.parse('{"data": {\
    "Meta Data": {\
        "1. Information": "Monthly Prices (open, high, low, close) and Volumes",\
        "2. Symbol": "MSFT",\
        "3. Last Refreshed": "2017-08-18",\
        "4. Time Zone": "US/Eastern"\
    },\
    "Monthly Time Series": {\
        "2017-08-18": {\
            "1. open": "73.1000",\
            "2. high": "74.1000",\
            "3. low": "71.2800",\
            "4. close": "72.4900",\
            "5. volume": "285933387"\
        },\
        "2017-07-31": {\
            "1. open": "69.3300",\
            "2. high": "74.4200",\
            "3. low": "68.0200",\
            "4. close": "72.7000",\
            "5. volume": "451248934"\
        }\
}}}');

console.log(Object.keys(data['data']["Monthly Time Series"]));

输出：

(2) ["2017-08-18", "2017-07-31"]

啊，经过您的编辑，如果您想循环遍历它们，您不需要使用 Object.keys 函数 - 您可以像这样简单地遍历对象：

for (var i in data['data']['Monthly Time Series'])
    console.log(i, data['data']['Monthly Time Series'][i])

i 将包含您的密钥

根据评论：
var obj = {"data": {
    "Meta Data": {
        "1. Information": "Monthly Prices (open, high, low, close) and Volumes",
        "2. Symbol": "MSFT",
        "3. Last Refreshed": "2017-08-18",
        "4. Time Zone": "US/Eastern"
    },
    "Monthly Time Series": {
        "2017-08-18": {
            "1. open": "73.1000",
            "2. high": "74.1000",
            "3. low": "71.2800",
            "4. close": "72.4900",
            "5. volume": "285933387"
        },
        "2017-07-31": {
            "1. open": "69.3300",
            "2. high": "74.4200",
            "3. low": "68.0200",
            "4. close": "72.7000",
            "5. volume": "451248934"
        }
}}}

Object.keys(obj.data["Monthly Time Series"]).map(function(key, index){ return obj.data["Monthly Time Series"][key]["1. open"]; });

从数组中获取一个值： ```html

要从数组中获取一个值：

```
(2) ["73.1000", "69.3300"]

或者：

Object.keys(obj.data["Monthly Time Series"]).map(function(key, index){ return Object.values(obj.data["Monthly Time Series"][key]); });

获取所有值（虽然它们不会被连接起来）

如何访问“Monthly time series”中“1.open”的值？如果我重复上述方法，它会显示未定义。 - Aayushi
1. open isn't within Monthly time series - it's data['data']['Monthly Time Series']['2017-07-31']['1. open'] - eithed
我做了类似这样的事情：Object.keys(response.data['Monthly Time Series']).forEach(function(k){ console.log(Object.keys(k["1. open"])); 它在控制台上显示未定义。 - Aayushi
请说明您想要做什么 - 目前您正在获取forEach循环结果的键，这实际上返回undefined（forEach始终返回undefined）。您是否想要获取“月度时间序列”中最低级别的值？ - eithed
是的，我想获取每月时间序列中最低级别的值。 - Aayushi
网页内容由stack overflow 提供, 点击上面的
可以查看英文原文，
原文链接