คำนวณอายุ แบบไทย (ปี พศ)

function calcAge(date, month, year) {
     month = month - 1;
     year = year - 543;

     today = new Date();
     dateStr = today.getDate();
     monthStr = today.getMonth();
     yearStr = today.getFullYear();

     theYear = yearStr - year;
     theMonth = monthStr - month;
     theDate = dateStr - date;

     var days = "";
     if (monthStr == 0 || monthStr == 2 || monthStr == 4 || monthStr == 6 || monthStr == 7 || monthStr == 9 || monthStr == 11) days = 31;
     if (monthStr == 3 || monthStr == 5 || monthStr == 8 || monthStr == 10) days = 30;
     if (monthStr == 1) days = 28;

     inYears = theYear;

     if (month < monthStr && date > dateStr) { 
          inYears = parseInt(inYears) + 1;
          inMonths = theMonth - 1; 
     };
     
     if (month < monthStr && date <= dateStr) {
          inMonths = theMonth; 
     } else if (month == monthStr && (date < dateStr || date == dateStr)) { 
          inMonths = 0; 
     } else if (month == monthStr && date > dateStr) { 
          inMonths = 11; 
     } else if (month > monthStr && date <= dateStr) { 
          inYears = inYears - 1;
          inMonths = ((12 - -(theMonth)) + 1); 
     } else if (month > monthStr && date > dateStr) { 
          inMonths = ((12 - -(theMonth))); 
     };
     
     if (date < dateStr) { 
          inDays = theDate; 
     } else if (date == dateStr) { 
          inDays = 0; 
     } else { 
          inYears = inYears - 1; 
          inDays = days - (-(theDate)); 
     };
     
     var result = ['day', 'month', 'year'];
     result.day = inDays;
     result.month = inMonths;
     result.year = inYears;
     
     return result;
};