ขอถามหน่อยครับเรื่อง javascript จาก ตัวแปร จะให้มันรับค่ามาก่อนควรทำไงอะครับจาก code ตย นี้อะครับ

 function CreateNewRow()
    {
        var intLine = parseInt(document.form1.hdnMaxLine.value);
        intLine++;
            
        var theTable = document.all.tbExp
        var newRow = theTable.insertRow(theTable.rows.length)
        newRow.id = newRow.uniqueID
        
        var item1 = 1
        var newCell
        
        //*** Column 1 ***//
        newCell = newRow.insertCell(0)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = " <tr><td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"7\" NAME=\"item19"+intLine+"\" VALUE=\"\" CLASS=\"textb11\" ID=\"item19\"></div></td>"

        //*** Column 2 ***//
        newCell = newRow.insertCell(1)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = "<td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"60\" MAXLENGTH=\"45\" NAME=\"desc19"+intLine+"\" VALUE=\"\" CLASS=\"textb11\" ID=\"desc19\"></div></td>"     
        
        //*** Column 3 ***//
        newCell = newRow.insertCell(2)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = "<td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"20\" NAME=\"quantity19"+intLine+"\" VALUE=\"\" CLASS=\"textb11\" onkeyup=\"calAmount2()\" ID=\"quantity19\"></div></td>"             
        
        //*** Column 4 ***//
        newCell = newRow.insertCell(3)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = "<td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"7\" NAME=\"unit173"+intLine+"\" VALUE=\"\" CLASS=\"textb11\" ID=\"unit173\"></div></td>"     
        
        //*** Column 5 ***//
        newCell = newRow.insertCell(4)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = "<td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"8\" NAME=\"unit_price19"+intLine+"\" VALUE=\"\" CLASS=\"textb11\" ID=\"unit_price19\"></div></td>" 
         newCell = newRow.insertCell(5)
        newCell.id = newCell.uniqueID
        newCell.setAttribute("className", "css-name");
        newCell.innerHTML = "<td><div align=center><INPUT TYPE=\"TEXT\" SIZE=\"20\" NAME=\"amount19"+intLine+"\" VALUE=\"0\" CLASS=\"textb11\" onblur=\"calTotal()\" ID=\"amount19\"></div></td></tr>"          
        

        document.form1.hdnMaxLine.value = intLine;
    }

function  calTotal(){
var a1=document.form1.amount1.value;
var a2=document.form1.amount2.value;
var a3=document.form1.amount3.value;
var a4=document.form1.amount4.value;
var a5=document.form1.amount5.value;
var a6=document.form1.amount6.value;
var a7=document.form1.amount7.value;
var a8=document.form1.amount8.value;
var a9=document.form1.amount9.value;
var a10=document.form1.amount10.value;
var a11=document.form1.amount11.value;
var a12=document.form1.amount12.value;
var a13=document.form1.amount13.value;
var a14=document.form1.amount14.value;
var a15=document.form1.amount15.value;
var a16=document.form1.amount16.value;
var a17=document.form1.amount17.value;
var a18=document.form1.amount18.value;
var a19=document.form1.amount19."+iniLine+".value; // แบบถูกไหมครับ
var t=0;
if(a1.length >0 || a2.length > 0 || a3.length > 0 || a4.length > 0 || a5.length > 0 || a6.length > 0 || a7.length > 0 || a8.length > 0 || a9.length > 0 || a10.length > 0 || a11.length > 0 || a12.length > 0 || a13.length > 0 || a14.length > 0 || a15.length > 0 || a16.length > 0 || a17.length > 0 || a18.length > 0){
	//alert(startMile);
 t=parseFloat(a1)+parseFloat(a2)+parseFloat(a3)+ parseFloat(a4)+parseFloat(a5)+parseFloat(a6)+ parseFloat(a7)+parseFloat(a8)+parseFloat(a9)+ parseFloat(a10)+parseFloat(a11)+parseFloat(a12)+ parseFloat(a13)+parseFloat(a14)+parseFloat(a15)+ parseFloat(a16)+parseFloat(a17)+parseFloat(a18);
}
document.form1.total.value=t;
}