将数组键推送到自己的数组答案

【问题标题】：push array key to own array将数组键推送到自己的数组
【发布时间】：2017-04-28 01:50:35
【问题描述】：

我正在努力研究如何将我的数组键推送到我最终将用作列标题的数组中。

以下成功记录了我的密钥，但是推送中断了

    let cols = []

    data.forEach(function (obj, index) {
      if (index === 0)
      {
        console.log(Object.keys(obj));
        this.cols.push(Object.keys(obj));
    }
    });

我实际上不必循环整个数据对象，我只需要第一个索引，但一次需要一个步骤！

我期望的最终结果是 cols = ["ValueDate", "AccountName", "Holding"]

大家有什么意见

感谢GWS

数据提取：

[
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHAUD",
    "Holding": 318622.53
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHCAD",
    "Holding": 7195
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHEUR",
    "Holding": 5077.97
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHGBP",
    "Holding": 19625
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHJPY",
    "Holding": 16463
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHNZD",
    "Holding": 601.56
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHSGD",
    "Holding": 1000
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHUSD",
    "Holding": 1716906.25
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHAUD",
    "Holding": 318622.53
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHCAD",
    "Holding": 7195
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHEUR",
    "Holding": 5077.97
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHGBP",
    "Holding": 19625
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHJPY",
    "Holding": 16463
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHNZD",
    "Holding": 601.56
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHSGD",
    "Holding": 1000
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHUSD",
    "Holding": 1720781.25
  }
]

【问题讨论】：

Object.keys() 返回一个数组，所以这可能有助于stackoverflow.com/questions/4156101/…
let cols = Object.keys(data[0]) 不行吗？
Saravanas 解决方案和 Anis 一样工作

标签： javascript arrays typescript key

【解决方案1】：

如果您无论如何只需要查看第一个索引，只需使用Object.keys(data[0])。请参阅下面的工作示例。

data = [
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHAUD",
    "Holding": 318622.53
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHCAD",
    "Holding": 7195
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHEUR",
    "Holding": 5077.97
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHGBP",
    "Holding": 19625
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHJPY",
    "Holding": 16463
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHNZD",
    "Holding": 601.56
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHSGD",
    "Holding": 1000
  },
  {
    "ValueDate": "2017-04-26T14:16:00",
    "AccountName": "CASHUSD",
    "Holding": 1716906.25
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHAUD",
    "Holding": 318622.53
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHCAD",
    "Holding": 7195
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHEUR",
    "Holding": 5077.97
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHGBP",
    "Holding": 19625
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHJPY",
    "Holding": 16463
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHNZD",
    "Holding": 601.56
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHSGD",
    "Holding": 1000
  },
  {
    "ValueDate": "2017-04-27T14:16:00",
    "AccountName": "CASHUSD",
    "Holding": 1720781.25
  }
]

let cols = Object.keys(data[0])
console.log(cols)

【讨论】：

【解决方案2】：

使用

for(var key in obj){
}

data.forEach(function (obj, index) {
  if(index == 0){
    for(var key in obj){
       console.log(key);
    }
  }  
});

遍历对象并获取键值

【讨论】：

【解决方案3】：

让 cols = []

data.forEach(function (obj, index) {
  if (index === 0)
  {
    console.log(Object.keys(obj));
    cols.push(Object.keys(obj));
 }
});

console.log(cols)

【讨论】：