用jQuery选择第一个“ n”个日期

Question

我从这样的API得到响应

{
    "Meta Data": {
        "1. Information": "Daily Time Series with Splits and Dividend Events",
        "2. Symbol": "NSE:TECHM",
        "3. Last Refreshed": "2019-09-06",
        "4. Output Size": "Full size",
        "5. Time Zone": "US/Eastern"
    },
    "Time Series (Daily)": {
        "2019-09-06": {
            "1. open": "716.3500"
        },
        "2019-09-05": {
            "1. open": "710.0000"
        },
        "2019-09-04": {
            "1. open": "705.0000"
        },
        "2019-09-03": {
            "1. open": "698.0000"
        },
        "2019-08-30": {
            "1. open": "693.0000"
        }
    }
}

我需要从响应的“时间序列（每日）”部分获取前3个日期。 .slice（0,3）无效，因为它包含日期。

Answer 1

不能保证对象中键的顺序。因此， first three是相对术语。 您可以使用Object.keys从"Time Series (Daily)"对象中获取键，并对其进行迭代以获取值

 let data = { "Meta Data": { "1. Information": "Daily Time Series with Splits and Dividend Events", "2. Symbol": "NSE:TECHM", "3. Last Refreshed": "2019-09-06", "4. Output Size": "Full size", "5. Time Zone": "US/Eastern" }, "Time Series (Daily)": { "2019-09-06": { "1. open": "716.3500" }, "2019-09-05": { "1. open": "710.0000" }, "2019-09-04": { "1. open": "705.0000" }, "2019-09-03": { "1. open": "698.0000" }, "2019-08-30": { "1. open": "693.0000" } } } let newData = Object.keys(data["Time Series (Daily)"]); for (let x = 0; x <= 2; x++) { console.log(data["Time Series (Daily)"][newData[x]]) } 

Answer 2

由于不能保证对象中键的顺序，因此可以使用Object.entries()获取存储在键"Time Series (Daily)"中的对象条目。 然后，您可以根据日期以降序对该数组进行.sort() ，使其按降序排列，然后使用.slice(0, n)从数组中获取前n项目。 最后，您可以将所有这些内容封装在Object.fromEntries() ，这将从条目数组中构建一个对象：

 const data = { "Meta Data": { "1. Information": "Daily Time Series with Splits and Dividend Events", "2. Symbol": "NSE:TECHM", "3. Last Refreshed": "2019-09-06", "4. Output Size": "Full size", "5. Time Zone": "US/Eastern" }, "Time Series (Daily)": { "2019-09-06": { "1. open": "716.3500" }, "2019-09-05": { "1. open": "710.0000" }, "2019-09-04": { "1. open": "705.0000" }, "2019-09-03": { "1. open": "698.0000" }, "2019-08-30": { "1. open": "693.0000" } } } const get_dates = (obj, n) => Object.fromEntries(Object.entries(obj["Time Series (Daily)"]) .sort(([a], [b]) => new Date(b) - new Date(a)) .slice(0, n)); const res = get_dates(data, 3); console.log(res);