javascript - 如何添加新 key :value pair to an existing Javascript object dynamically within a loop

Question

我想根据两个对象计算一个新值，并将结果作为新对象添加到现有数组中。

输入内容如下:

[{
    "trades": [
        {
        "fields": {
                "orderOpenPrice": "1.40000",
                "orderTakeProfit": "1.50000",
                [...]

        },
        },

        {
          "fields": {
                "orderOpenPrice": "1.30000",
                "orderTargetPrice": "1.50000",
                [...]
        }
        },
        {
        "fields": {
                "orderOpenPrice": "1.50000",
                "orderTargetPrice": "1.55000",
                [...]
        }
        },

        [...]

}]

这是所需的输出:

[{
    "trades": [
        {
        "fields": {
                "orderOpenPrice": "1.40000",
                "orderTakeProfit": "1.50000",
                "pipsTargetedKey": "10000",
                [...]

        },
        },

        {
          "fields": {
                "orderOpenPrice": "1.30000",
                "orderTakeProfit": "1.50000",
                "pipsTargetedKey": "20000",
                [...]
        }
        },
        {
        "fields": {
                "orderOpenPrice": "1.50000",
                "orderTakeProfit": "1.55000",
                "pipsTargetedKey": "5000",
                [...]
        }
        },

        [...]

}]

我使用此线程尝试了两种不同的方法:How can I add a key/value pair to a JavaScript object? :

使用分配:

[...]
for (var i = 0; i < tradesTotal; i++) {
    pipsTargeted = Math.abs(trades[i].fields.orderOpenPrice - trades[i].fields.orderTakeProfit);
    trades[i].fields.assign(trades[i].fields, {pipsTargetedKey: pipsTargeted});
}
[...]

使用点表示法:

[...]
for (var i = 0; i < tradesTotal; i++) {
    pipsTargeted = Math.abs(trades[i].fields.orderOpenPrice - trades[i].fields.orderTakeProfit);
    trades[i].fields.pipsTargetedKey = pipsTargeted
}
[...]

但是，这两次尝试都没有添加另一个键:值对。

根据要求进行编辑:

tradesTotal = Object.keys(trades).length;

// manipulate trades object
for (var i = 0; i < tradesTotal; i++) {

    // format dateTime
    trades[i].fields.orderOpenTime = (trades[i].fields.orderOpenTime).replace('T', ' ');
    if (trades[i].fields.orderCloseTime !== null)
    trades[i].fields.orderCloseTime = (trades[i].fields.orderCloseTime).replace('T', ' ');

    // format orderType
    if (trades[i].fields.orderType === 0) {
        trades[i].fields.orderType = 'Buy'
    } else if (trades[i].fields.orderType === 1) {
        trades[i].fields.orderType = 'Sell'
    } else if (trades[i].fields.orderType === 2) {
        trades[i].fields.orderType = 'Buy Limit'
    } else if (trades[i].fields.orderType === 3) {
        trades[i].fields.orderType = 'Sell Limit'
    } else if (trades[i].fields.orderType === 4) {
        trades[i].fields.orderType = 'Buy Stop'
    } else if (trades[i].fields.orderType === 5) {
        trades[i].fields.orderType = 'Sell Stop'
    } else if (trades[i].fields.orderType === 6) {
        trades[i].fields.orderType = 'Bank Transaction'
    }

    // calculate R:R and TP + SL in pips and add result to object
    if (stopLoss && takeProfit > 0) {
        pipsRisked = Math.abs(trades[i].fields.orderOpenPrice - trades[i].fields.orderStopLoss);
        pipsTargeted = Math.abs(trades[i].fields.orderOpenPrice - trades[i].fields.orderTakeProfit);
        rrRatio = (pipsTargeted / pipsRisked);
        trades[i].fields.pipsRiskedKey = pipsRisked;
        trades[i].fields.pipsTargetedKey = pipsTargeted;
        trades[i].fields.pipsRRKey = rrRatio;
    }
}

Answer 1

正如您提到的，trades 是一个数组。当您对数组执行 Object.keys() 操作时，您将获得该数组的索引。这可以简化为 trades.length 因为它们是相同的东西。

当前，您正在循环交易，这允许您访问数组中的每个对象。每个对象都有一个带有数组的 trades 属性，您也需要对其进行循环。这意味着您需要一个嵌套循环。一种是循环遍历较大对象中的所有对象，另一种循环遍历 trades 属性数组中的所有对象。这可以像这样完成:

const tradesTotal = [{
  "trades": [{
      "fields": {
        "orderOpenPrice": "1.40000",
        "orderTakeProfit": "1.50000",


      },
    },

    {
      "fields": {
        "orderOpenPrice": "1.30000",
        "orderTargetPrice": "1.50000",

      }
    },
    {
      "fields": {
        "orderOpenPrice": "1.50000",
        "orderTargetPrice": "1.55000",

      }
    },
  ]
}];


for (var i = 0; i < tradesTotal.length; i++) {
  var trades = tradesTotal[i].trades;
  for (var j = 0; j < trades.length; j++) {
    var pipsTargeted = Math.abs(trades[j].fields.orderOpenPrice - trades[j].fields.orderTakeProfit);
    trades[j].fields.pipsTargetedKey = pipsTargeted
  }

}
console.log(tradesTotal);