Question

Goal:
Evaluate a specifik value in my validation code

Problem:
The variable “currentValue” can retrieve a value named “NaN”. And i don’t know what kind of datatype that shall be applied in the my validation process.

Based on my previous test, NaN is neither a string or int or something similiar.

What datatype is NaN?

    var ddd = $('#field_timmar').val();
    //datac= $('#field_timmar').val();
    //len = currentValue.length;

    var currentValue = parseInt(ddd);


    // Validating message
    if(currentValue <= 0)
    {
        $('#field_timmar_error1').show();

        $('#field_timmar_error2').hide();
        $('#field_timmar_error3').hide();

        nonError = false;
    }
    else if(currentValue == "NaN" && ddd != "")
    {
        $('#field_timmar_error2').show();

        $('#field_timmar_error1').hide();
        $('#field_timmar_error3').hide();

        nonError = false;
    }
    else if(currentValue == "NaN" && ddd == "")
    {
        $('#field_timmar_error3').show();

        $('#field_timmar_error1').hide();
        $('#field_timmar_error2').hide();

        nonError = false;
    }       
    else
    {
        $('#field_timmar_error1').hide();
        $('#field_timmar_error2').hide();
        $('#field_timmar_error3').hide();
    }   

Answer 1

The data type of NaN is actually Number, but because of its special status, it cannot be directly compared with any other value. There is a function isNaN that lets you test whether a number is NaN:

if (isNaN(currentValue)) {
  ...
}