function ValidateISBN(isbn)
{
	var _tempISBN = Trim(isbn);
	var flag = false;
	if(_tempISBN == "")
	{
		alert("ISBN value required");
		return false;
	}
	if(_tempISBN.length == 10)
	{
		if(ValidateISBN10(_tempISBN) == true)return true;
		else  flag = true;
		
	}
	else if(_tempISBN.length == 13)
	{
		if(ValidateISBN13(_tempISBN) == true) return true;
		else  flag = true;
	}
	else flag = true;
	
	if( flag == true)
	{
		alert("ISBN entered is not a valid ISBN");
		return false;
	}
}

function ValidateISBN10(tempisbn)
{
	var WeighFactor = 10;
	var _Temp = 0;
	var CheckDigit = "0X987654321";
	var tempisbn1 = tempisbn.substr(0,8);
	if(IsNumeric(tempisbn1) == false) return false;
	for(var i = 0; i <= 8; i++)
	{
		var _Char = parseInt(tempisbn.charAt(i));
		_Temp = _Temp + (WeighFactor*_Char);
		WeighFactor = WeighFactor - 1;;
	}
	_Temp = _Temp % 11;
	var _tempchar9 = tempisbn.charAt(9);
	if(CheckDigit.charAt(_Temp) != _tempchar9.toUpperCase())
	{
		return false;
	}
	return true;	
}

function ValidateISBN13(tempisbn)
{
	var WeighFactor = 1;
	var _Temp = 0;
	if(IsNumeric(tempisbn) == false) return false;
	if(tempisbn.substr(0,3) == "978" || tempisbn.substr(0,3) == "979")
	{	
		for(var i = 0; i <= 11; i++)
		{
			var _Char = parseInt(tempisbn.charAt(i));
			_Temp = _Temp + (WeighFactor*_Char);
			if(WeighFactor == 1) WeighFactor = 3;
			else WeighFactor = 1;
		}
		_Temp = _Temp % 10;
		if(_Temp == 0 && tempisbn.charAt(12) == 0)	return true;
		else if((10 - _Temp) ==  tempisbn.charAt(12)) return true;
		else return false;
	}
	else return false;	
}

function GetISBN10FromISBN13(isbn)
{	if(isbn.length == 13 && ValidateISBN13(isbn) == true && isbn.substr(0,3) == "978")
	{
		var _TempISBN = isbn.substr(3,9);
		var WeighFactor = 10;
		var _Temp = 0;
		var CheckDigit = "0X987654321";
		for(var i = 0; i <= 8; i++)
		{
			var _Char = parseInt(_TempISBN.charAt(i));
			_Temp = _Temp + (WeighFactor*_Char);
			WeighFactor = WeighFactor - 1;
		}
		_Temp = _Temp % 11;
		return 	_TempISBN + CheckDigit.charAt(_Temp);
	}
	else if(isbn.length == 13 && ValidateISBN13(isbn) == true && isbn.substr(0,3) == "979")
	{
		return "";
	}
	else
	{	alert("ISBN entered is not a valid ISBN13");
		return "";
	}	
}

function GetISBN13FromISBN10(isbn)
{
	if(isbn.length == 10 && ValidateISBN10(isbn) == true)
	{
		var _TempISBN = "978" + isbn.substr(0,9);
		var WeighFactor = 1;
		var _Temp = 0;
		for(var i = 0; i <= 11; i++)
		{
			var _Char = parseInt(_TempISBN.charAt(i));
			_Temp = _Temp + (WeighFactor*_Char); 
			if(WeighFactor == 1) WeighFactor = 3;
			else WeighFactor = 1;
		}
		_Temp = _Temp % 10;
		if(_Temp == 0)	return _TempISBN + _Temp;
		else	return _TempISBN + (10-parseInt(_Temp));
	}
	else
	{
		alert("ISBN entered is not a valid ISBN10");
		return "";
	}
}

function Trim(TRIM_VALUE)
{
	if(TRIM_VALUE.length < 1) return"";
	TRIM_VALUE = RTrim(TRIM_VALUE);
	TRIM_VALUE = LTrim(TRIM_VALUE);
	if(TRIM_VALUE=="") return "";
	else return TRIM_VALUE;
}

function RTrim(VALUE)
{
	var w_space = String.fromCharCode(32);
	var v_length = VALUE.length;
	var strTemp = "";
	if(v_length < 0) return"";
	var iTemp = v_length -1;
	while(iTemp > -1)
	{
		if(VALUE.charAt(iTemp) == w_space){	}
		else
		{
			strTemp = VALUE.substring(0,iTemp +1);
			break;
		}
		iTemp = iTemp-1;
	}
	return strTemp;
}

function LTrim(VALUE)
{
	var w_space = String.fromCharCode(32);
	if(v_length < 1) return"";
	var v_length = VALUE.length;
	var strTemp = "";
	var iTemp = 0;

	while(iTemp < v_length)
	{
		if(VALUE.charAt(iTemp) == w_space){}
		else
		{
			strTemp = VALUE.substring(iTemp,v_length);
			break;
		}
		iTemp = iTemp + 1;
	}
	return strTemp;
}

function IsNumeric(strString)
{
   var strValidChars = "0123456789.-";
   var strChar;
   var blnResult = true;
   if (strString.length == 0) return false;
   for (i = 0; i < strString.length && blnResult == true; i++)
      {
      strChar = strString.charAt(i);
      if (strValidChars.indexOf(strChar) == -1)
         {
         blnResult = false;
         }
      }
   return blnResult;
}