Hi!!
This is some of the code I am using to add dynamic rows when user clicks the Add Row button.I want to show the calculated amount like:
line_total=qty*unit_price;
sub_total=total of line_total;
total=sub_total+tax-advance;

PHP Code:
<script type="text/javascript">
function 
addRow(tableID
{
            var 
table document.getElementById(tableID);
            var 
rowCount table.rows.length;
            if(
rowCount<3)
                {
                var 
row table.insertRow(rowCount);
                var 
colCount table.rows[0].cells.length;
                for(var 
i=0i<colCounti++)
                          {
                        var 
newcell row.insertCell(i);
                        
newcell.innerHTML table.rows[0].cells[i].innerHTML;
                        
//alert(newcell.childNodes);
                            
switch(newcell.childNodes[0].type
                            {
                            case 
"text":
                                
newcell.childNodes[0].value "";
                            break;
                            case 
"checkbox":
                                
newcell.childNodes[0].checked false;
                            break;
                            case 
"select-one":
                                
newcell.childNodes[0].selectedIndex 0;
                            break;
                            }
                        }
                }

        else 
        {
        
alert("Maximum Limit Of 3 Rows Reached");
        }
}
function 
deleteRow(tableID)
{
            try
                 {
                var 
table document.getElementById(tableID);
                var 
rowCount table.rows.length;

                    for(var 
i=0i<rowCounti++) 
                        {
                        var 
row table.rows[i];
                        var 
chkbox row.cells[0].childNodes[0];
            
                        if (
null != chkbox && true == chkbox.checked
                            {
                            if (
rowCount <= 1
                                {
                                
alert("Cannot delete all the rows.");
                                break;
                                }
                
                            
table.deleteRow(i);
                            
rowCount--;
                            
i--;
                            }

                        }
                    } catch(
e
                        {
                        
alert(e);
                        }
}
</script>
<form name="newquotation1" method="post" action="invoice_data.php" onSubmit="return validateForm(this)">
<tr>
<td><input type="button" value="Add Row" onClick="addRow('dataTable')" ></td>
<table align="center" id="dataTable" width="912">
<tr>
<td width="68">Quantity:</td>
<td width="144"><input type="text" name="qty[]" id="qty"></td>
<td width="77">Description:</td>
<td width="144"><input type="text" name="description[]" id="description"></td>
<td width="80">Unit Price:</td>
<td width="144"><input type="text" name="unit_price[]" id="unit_price"></td>
<td width="75">Line Total:</td>
<td width="144"><input type="text" name="line_total[]" id="line_total" onBlur="return line(this)" readonly""></td>
</tr>
</table>
<table align="center" width="913">
<tr>
<td width="67">Subtotal:</td>
<td width="146"><input type="text" name="subtotal" id="subtotal" readonly""></td>
<td width="75">Taxes:</td>
<td width="144"><input type="text" name="tax" id="tax"></td>
<td width="81">Advance:</td>
<td width="144"><input type="text" name="advance" id="advance"></td>
<td width="76">Total:</td>
<td width="144"><input type="text" name="total" id="total" onBlur="return tot(this)" readonly""></td>
</tr>
</table>
<table align="center">
<tr>
<td><input name="submit" type="submit" value="Submit"></td>
</tr>
</table>
</form> 
So far I came up with the function as follows.It works very well on the first row, but not on the other dynamically added rows.
Similarly, I dont know how I can calculate the sub_total value by adding line_total feilds altogether.Please help me out
PHP Code:
<script type="text/javascript">
function 
line(elem) {
var 
a=document.getElementById("qty").value;
var 
qt=Number(a); 
var 
b=document.getElementById("unit_price").value;
var 
up=Number(b); 
var 
c=qt*up;
document.getElementById("line_total").value c;
}

function 
tot(elem) {
var 
d=document.getElementById("subtotal").value;
var 
st=Number(d); 
var 
e=document.getElementById("tax").value;
var 
tx=Number(e); 
var 
f=document.getElementById("advance").value;
var 
ad=Number(f); 
var 
g=(st+tx)-ad;
document.getElementById("total").value g;
}
</script>