如何检查json字符串中是否存在NAN

Question

suppose i have below function, which is getting jsonData in the form of jason, i validate the var jsonData to check for NaN ?

function save() {
        var jsonData = getEnteredValue(); 
        $.ajax({
            type : 'POST',
            url : 'saveSalesForecast.json',
            data : 'jsonPostData=' + jsonData,
            success : function() { //alert("success");
            }
        });
    }

i only know how to replace NAN but don know how to check for NAN!

jsonData = JSON.parse(jsonData.replace(/\bNaN\b/g, "null"));

here is remaining function:(any field values can be string,numbers but it should not be NAN

  function getEnteredValue() {
    var rowIds = $("#salesForecastGrid").jqGrid('getDataIDs');
    var ids=[];
    var jsonPostData = "[";

    for ( var i = 0; i <= rowIds.length-1; i++) {
    $("#salesForecastGrid").jqGrid('editCell', i, 2, false);
        var forecastedSales = parseFloat($("#salesForecastGrid")
                .jqGrid('getCell', rowIds[i], 'forecastedSales'));

        if (!((forecastedSales == "") || isNaN(forecastedSales) || (forecastedSales ==0))) {
            if (ids.indexOf(rowIds[i])==-1){
                ids.push(rowIds[i]);
                }
            }
    }



    for ( var i = 0; i <= ids.length-1; i++) {
        var forecastedSales = parseFloat($("#salesForecastGrid")
                .jqGrid('getCell', ids[i], 'forecastedSales'));
        var id = $("#salesForecastGrid").jqGrid('getCell', ids[i],
                'id');
        var date = $("#salesForecastGrid").jqGrid('getCell',
                ids[i], 'day');
        if (id < 0) {
            id = 0;
        }

        var record = "{" + "id:" + id + "," + "date:" + date + ","
                + "forecastedSales:" + forecastedSales + "}";
        jsonPostData = jsonPostData + record;
        if (i != ids.length) {
            jsonPostData = jsonPostData + ",";
        }
    }
    jsonPostData += "]";
    return jsonPostData;
}

Json Data like:

"[{id:68447,date:04-17-2014,forecastedSales:8420.42},{id:68448,date:04-18-2014,‌​forecastedSales:9912.68},]"

Answer 1

Your problem is that you are creating the JSON manually, and thus end up with invalid JSON. Do yourself a favor and use JSON.stringify :

function getEnteredValue() {
    var rowIds = $("#salesForecastGrid").jqGrid('getDataIDs');
    var ids=[];
    var data = [];

    // ...


    for ( var i = 0; i < ids.length; i++) {
        // ...

        data.push(
           {id: id, date: date, forecastedSales: forecastedSales}
        );
    }
    return JSON.stringify(data);
}

Since NaN is not a valid value in JSON, it will automatically be converted to null . Example:

> JSON.stringify({a: NaN});
  "{"a":null}"

---

For more info see Using native JSON .

Answer 2

NaN is not acceptable in JSON. JSON specification does not support NaN as a value. Even when javascript object has NaN value, it will be converted to null when you serialise to JSON format.

First of all, JSON is not an Javascript Object. JSON is general format which can be understand by all languages.