Javascript to sum fields in gridview not working

I have some javascript functions that run on the onkeyup event of some textboxs in a gridview.   Now I'm trying to add an additional function to sum some more.  I'm getting an error on page at the bottom of the browser when the event fires.  The error lists at the line before my new function and says "Object does not support this property or method".

My code is shown below.  The new function I'm adding in SumItUpB.  The other functions still work good (Thanks to some previous help from Experts-Exchange).
The javascript code
 function SumItUp(textResult)
				var x = 0;
				var y = 0;
				var z = 0;
				var myArray = new Array();
				//add array items, this calls the public server variable we build in rowdatabound
				<%= JSArray %>
				//sum it:
				for (x = 0; x < myArray.length; x++)
				    //multiply the value times one to trick js into always thinking the variable is a number
				    y = y + (myArray[x] * 1.00);
				//display the result
				z = (y * 1);
			    document.getElementById(textResult).value = z.toFixed(2);
				//document.getElementById(textResult).value = (y * 1.00);
			function SumItUpB(textResult)
	         var x = 0;
			 var y = 0;
			  var myArray2 = new Array();
			  <%= JSArray2 %>
			  for (x = 0; x < myArray2.length; x++);
			        y = y + (myArray2[x] * 1.00);
			  document.getElementById(textResult).value = (y * 1);
			function Multiply(text1, text2, textResult)
				var x = document.getElementById(text1).value;
				var y = document.getElementById(text2).value;
				if(IsNumeric(x) == true && IsNumeric(y) == true)
				document.getElementById(textResult).value = (x * 1) * (y * 1.00);
				document.getElementById(textResult).value = '';
			function IsNumeric(sText)
               var ValidChars = "0123456789.-";
               var IsNumber=true;
               var Char;
               for (i = 0; i < sText.length && IsNumber == true; i++) 
                  Char = sText.charAt(i); 
                  if (ValidChars.indexOf(Char) == -1) 
                     IsNumber = false;
               return IsNumber;
The C# Code:
 protected void gvMealsForSell_RowDataBound(object sender, GridViewRowEventArgs e)
        if (e.Row.RowType == DataControlRowType.DataRow)
            // Get values for calculation
            TextBox txtQuantity = (TextBox)e.Row.FindControl("txtNumberToBuy"); // quantity
            HiddenField hfMealPrice = (HiddenField)e.Row.FindControl("hfMealPrice"); // meal price
            HiddenField hfTotal = (HiddenField)e.Row.FindControl("hfTotal"); //total 
            txtQuantity.Text = "0"; // Default value
            // Add javascript to text box with calcualtion values
            txtQuantity.Attributes.Add("onkeyup", "javascript:Multiply('" + txtQuantity.ClientID + "','" + hfMealPrice.ClientID + "','" + hfTotal.ClientID + "');SumItUp('" + this.txtTotalDue.ClientID + "');SumItUpB('" + this.txtTotalItems.ClientID + "')");
            //Set up javascript array
            JSArray  += "myArray[" + counter.ToString() + "] = document.getElementById('" + hfTotal.ClientID + "').value;" + Environment.NewLine;
            JSArray2 += "myArray2[" + counter.ToString() + "] = document.getElemenetById('" + txtQuantity.ClientID + "').text;" + Environment.NewLine;
            //counter to maintain the js array index
            counter += 1; 

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Pravin AsarPrincipal Systems EngineerCommented:
To do math operations on the variable values, it is a good idea to parse as Float


var x= 1.0;
var y = "2.5";

var sum = parseFloat(x) + parseFloat(y);
alert (sum);

So where you are trying to add/multiply the variable, please use parseFloat

weimhaAuthor Commented:
I've decided not to do this.
Thanks for the input.

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