javascript - 将特定的json元素转换为json中的数字

Question

我有以下 json 对象:

[{
    "WEIGHTED_ARR_LAST_SLP": "0.03801186624130076",
    "SLIPPAGE_INTERVAL_VWAP_BPS": "10.2711",
    "ROOT_ORDER_ID": "735422197553491",
    "ARRIVAL_MID_PX": "93.6100",
    "WEIGHTED_ARR_SLP": "0.12323190317127024",
    "AVG_PX": "93.6586",
    "LEAVES_QTY": "0",
    "WEIGHT": "0.02372627566400397",
    "PARTICIPATION_RATE": "0E-12",
    "LOCAL_REF_END_TIME": "2016-09-06 06:00:27.775",
    "WEIGHTED_IVWAP_SLP": "0.2436949499725512",
    "NOTIONAL_USD": "477940",
    "LIQ_CONSUMPTION": "15.21",
    "EXEC_QTY": "5103",
    "CL_ORD_ID": "7245294057012908344",
    "LOCAL_REF_START_TIME": "2016-09-06 05:59:57.844",
    "SLIPPAGE_END_LAST_ARR_LAST_BPS": "1.6021",
    "IVWAP_PX": "93.5625",
    "LIMIT_PX": "93.6100",
    "ORDER_ID": "735422197553491",
    "SLIPPAGE_ARR_MID_BPS": "5.1939",
    "ORDER_QTY": "5103",
    "EXECUTION_STYLE": "2", {"ORDER_QTY": "5100", ..........}
}]

我只想转换“Ord Qty”、“Exec Qty”、“AVG Px”、“Notional”、“Limit Px”、“Arrival Px”、“Arrival Px Slpg”、“IVWAP Px Slpg” ，“LIQ 消耗” 为数字；然后显示 WEIGHTED_IVWAP_SLP 和 WEIGHTED_ARR_SLP 为 4 位小数，而不是那么多。我试图通过以下方式做到这一点:

var jsondata = document.getElementById("jsonArray").value;
var jsondataObj = JSON.parse(jsondata);

function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}

var parsedData = jsondataObj.map(function(obj) {
    return Object.keys(obj).reduce(function(memo, key) {
        var value = obj[key];
        //console.log(value);
        memo[key] = isNumeric(value) ? Number(value).toFixed(4) : value;
        //localStorage.setItem("storeditem", value);

        return memo;
    }, {})
});

但这正在转换所有具有 4 位小数点的数字字段。如何只转换特定字段？

Answer 1

这算是为你做你的工作吧？好吧，这个答案不使用您的代码，但您应该能够同样应用它。这使用诸如 if 之类的语言结构。 , for和 for ... in与 Array 的方法相反像map , reduce ，和filter .

var a = [{
  "WEIGHTED_ARR_LAST_SLP": "0.03801186624130076",
  "SLIPPAGE_INTERVAL_VWAP_BPS": "10.2711",
  "ROOT_ORDER_ID": "735422197553491",
  "ARRIVAL_MID_PX": "93.6100",
  "WEIGHTED_ARR_SLP": "0.12323190317127024",
  "AVG_PX": "93.6586",
  "LEAVES_QTY": "0",
  "WEIGHT": "0.02372627566400397",
  "PARTICIPATION_RATE": "0E-12",
  "LOCAL_REF_END_TIME": "2016-09-06 06:00:27.775",
  "WEIGHTED_IVWAP_SLP": "0.2436949499725512",
  "NOTIONAL_USD": "477940",
  "LIQ_CONSUMPTION": "15.21",
  "EXEC_QTY": "5103",
  "CL_ORD_ID": "7245294057012908344",
  "LOCAL_REF_START_TIME": "2016-09-06 05:59:57.844",
  "SLIPPAGE_END_LAST_ARR_LAST_BPS": "1.6021",
  "IVWAP_PX": "93.5625",
  "LIMIT_PX": "93.6100",
  "ORDER_ID": "735422197553491",
  "SLIPPAGE_ARR_MID_BPS": "5.1939",
  "ORDER_QTY": "5103",
  "EXECUTION_STYLE": "2"
}];
var fieldsToConvertToNumbers = [
  "ORDER_QTY", "EXEC_QTY", "AVG_PX",
  "NOTIONAL_USD", "LIMIT_PX", "ARRIVAL_MID_PX",
  "WEIGHTED_IVWAP_SLP", "LIQ_CONSUMPTION"
];
for (var i = 0; i < a.length; ++i) {
  var b = a[i];
  for (var j = 0; j < fieldsToConvertToNumbers.length; ++j) {
    var field = fieldsToConvertToNumbers[j];
    if (field in b) {
      var value = parseFloat(b[field]);
      if (!isNaN(value))
        b[field] = value;
    }
  }
}
var pre = document.createElement("pre");
pre.appendChild(document.createTextNode(JSON.stringify(a, null, ' ')));
document.body.appendChild(pre);

使用parseFloat将值转换为数字，但请务必检查 NaN决定更新值之前的结果。使用IsNaN为了那个原因。不要认为您真的需要使用 ! IsFinite ，但要让自己崩溃。

所以现在你想使用 toFixed修复字符串显示。

var text = (3.1415926535897932384626433832795028841971).toFixed(4);
var pre = document.createElement("pre");
pre.appendChild(document.createTextNode(text));
document.body.appendChild(pre);

现在您可以使用toFixed将数字转换为只有 4 位小数精度的字符串。但是，它们是字符串而不是数字。所以你必须使用 parseFloat 解析它们。 .

var a = [{
  "WEIGHTED_ARR_LAST_SLP": "0.03801186624130076",
  "SLIPPAGE_INTERVAL_VWAP_BPS": "10.2711",
  "ROOT_ORDER_ID": "735422197553491",
  "ARRIVAL_MID_PX": "93.6100",
  "WEIGHTED_ARR_SLP": "0.12323190317127024",
  "AVG_PX": "93.6586",
  "LEAVES_QTY": "0",
  "WEIGHT": "0.02372627566400397",
  "PARTICIPATION_RATE": "0E-12",
  "LOCAL_REF_END_TIME": "2016-09-06 06:00:27.775",
  "WEIGHTED_IVWAP_SLP": "0.2436949499725512",
  "NOTIONAL_USD": "477940",
  "LIQ_CONSUMPTION": "15.21",
  "EXEC_QTY": "5103",
  "CL_ORD_ID": "7245294057012908344",
  "LOCAL_REF_START_TIME": "2016-09-06 05:59:57.844",
  "SLIPPAGE_END_LAST_ARR_LAST_BPS": "1.6021",
  "IVWAP_PX": "93.5625",
  "LIMIT_PX": "93.6100",
  "ORDER_ID": "735422197553491",
  "SLIPPAGE_ARR_MID_BPS": "5.1939",
  "ORDER_QTY": "5103",
  "EXECUTION_STYLE": "2"
}];
var fieldsToConvertToNumbers = [
  "ORDER_QTY", "EXEC_QTY", "AVG_PX",
  "NOTIONAL_USD", "LIMIT_PX", "ARRIVAL_MID_PX",
  "LIQ_CONSUMPTION"
];
var fieldsToConvertToFixedNumbers = [
  "WEIGHTED_IVWAP_SLP", "WEIGHTED_ARR_SLP"
];
for (var i = 0; i < a.length; ++i) {
  var b = a[i];
  for (var j = 0; j < fieldsToConvertToNumbers.length; ++j) {
    var field = fieldsToConvertToNumbers[j];
    if (field in b) {
      var value = parseFloat(b[field]);
      if (!isNaN(value))
        b[field] = value;
    }
  }
  for (var j = 0; j < fieldsToConvertToFixedNumbers.length; ++j) {
    var field = fieldsToConvertToFixedNumbers[j];
    if (field in b) {
      var value = parseFloat(b[field]);
      if (!isNaN(value))
        b[field] = parseFloat(value.toFixed(4));
    }
  }
}
var pre = document.createElement("pre");
pre.appendChild(document.createTextNode(JSON.stringify(a, null, ' ')));
document.body.appendChild(pre);

所以现在只有特定字段有 4 位小数。它们是数字，而不是字符串。