function checkNull (columnName, errorMsg) {
	var svalue = columnName.value;
	while (svalue.indexOf(" ") != -1){ 
		svalue=svalue.replace(" ","");
	}
	if (svalue == ""){
		alert(errorMsg);
		columnName.focus();
		return false;
	} else {
		return true;
	}
}
function checkIsNaN (columnName, errorMsg) {
	var nvalue = columnName.value;
	while (nvalue.indexOf(" ") != -1){ 
		nvalue=nvalue.replace(" ","");
	}
	if (isNaN(nvalue) || nvalue.length == 0){
		alert("1");
		alert(errorMsg);
		columnName.focus();
		return false;
	} else {
		alert("2");
		return true;
	}
}
function checkChecked (columnName, errorMsg) {
	var o = 0;
	var j = columnName.length;
	for (i = 0; i < j; i++)	{
		if (columnName[i].checked) {
			o++;
		}
	}
	if (o == 0) {
		alert(errorMsg);
		columnName[0].focus();
		return false;
	}else {
		return true;
	}
}
function checkMaxLength(columnName, max, errorMsg) {
	if (columnName.value.length > max){
		alert(errorMsg);
		columnName.focus();
		return false;
	} else {
		return true;
	}
}
function checkStrLength(columnName, length, errorMsg) {
	if (columnName.value.length != length){
		alert(errorMsg);
		columnName.focus();
		return false;
	} else {
		return true;
	}
}

function checkDate(YYYY, MM, DD, errorMsg){
    var y = parseInt(YYYY);
    var m = parseInt(MM);
    var d = parseInt(DD);

    var dt = new Date(y,m,1);
    dt.setDate(dt.getDate()-1);
    var maxday = dt.getDate();
    if(d>maxday){
		alert(errorMsg);
        return false;
    }
    return true;
}
function checkFormatDate(dateString, errorMsg) {
    var ok = false;
	var len = dateString.length;
	var y = dateString.substring(0,4);
	var m = dateString.substring(5,7);
	var d = dateString.substring(8,10);
	var s1 = dateString.substring(4,5);
	var s2 = dateString.substring(7,8);
	if (len != 10) {alert(errorMsg);return false;}
	if (s1 != '/' || s2 != '/') {alert(errorMsg);return false;}
	if (isNaN(y) || isNaN(m) || isNaN(d)) {alert(errorMsg);return false;}
	return checkDate(y,m,d,errorMsg);
}

function IsNumeric(strString)
   //  check for valid numeric strings	
   {
   //var strValidChars = "0123456789.-";
   var strValidChars = "0123456789";
   var strChar;
   var blnResult = true;

   if (strString.length == 0) return false;

   //  test strString consists of valid characters listed above
   for (i = 0; i < strString.length && blnResult == true; i++)
      {
      strChar = strString.charAt(i);
      if (strValidChars.indexOf(strChar) == -1)
         {
         blnResult = false;
         }
      }
   return blnResult;
   }