[SOLVED] Java addition

[M.O.S. Studios]

Hey guys,

i have a code that alters invoices on a shopping cart im making, and for some reason its math is a little odd

 

this is what it is displaying:

Subtotal:  18

Shipping:  1.80

Tax 1:      .9

Tax 2:    1.42

Tax 3:      .61

Total :    22.729999999999997

 

as you can see that math dosn't make scene, any one know what the problem could be?

 

funtion

 

  <SCRIPT language="JavaScript">
  function Calculate()
  {
   myform.Cost1.value = myform.Qty1.value * myform.Price1.value;

   myform.subtotal.value = parseFloat(myform.Cost1.value);
   myform.total.value =  parseFloat(myform.subtotal.value) + parseFloat(myform.shipping.value) + parseFloat(myform.tax1.value) + parseFloat(myform.tax2.value) + parseFloat(myform.tax3.value);

  }
  </SCRIPT>

 

<form NAME="myform" method="POST" action="account.php?actions=altsales">
<br><br>
<table width="100%" border="0" cellpadding="0" cellspacing="0">
<tr width='100%' height='50'><td align='center' width='20%'>ITEM NAME</td><td align='center' width='10%'>ITEM NUMBER</td><td align='center' width='20%'>CATAGORY</td><td align='center' width='10%'>QTY ORDERED</td><td align='center' width='10%'>QTY</td><td align='center' width='10%'>PRICE</td><td align='center' width='20%'>TOTAL AMOUNT</td></tr>
  <tr width='100%'><td align='center' width='20%'>Lapis Around You</td><td align='center' width='10%'>B120</td><td align='center' width='20%'>Necklaces</td><td align='center' width='10%'>1</td><td align='center' width='10%'><select NAME='Qty1' onChange='Calculate();'><option value='0' >0</option><option value='1' SELECTED>1</option><option value='2' >2</option><option value='3' >3</option><option value='4' >4</option><option value='5' >5</option><option value='6' >6</option><option value='7' >7</option><option value='8' >8</option><option value='9' >9</option><option value='10' >10</option><option value='11' >11</option><option value='12' >12</option><option value='13' >13</option><option value='14' >14</option><option value='15' >15</option><option value='16' >16</option><option value='17' >17</option><option value='18' >18</option><option value='19' >19</option></select></td><td align='center' width='10%'><INPUT TYPE='TEXT' SIZE='5' name='Price1' value='18.00' Readonly></td><td align='center' width='20%'><INPUT TYPE='TEXT' NAME='Cost1' SIZE='8' READONLY></td></tr>
<tr width='100%' height='50'><td align='center' width='20%'></td><td align='center' width='10%'></td><td align='center' width='20%'></td><td align='center' width='10%'></td><td align='center' width='10%'></td><td align='center' width='10%'></td><td align='center' width='20%'>Subtotal: <INPUT TYPE="TEXT" NAME="subtotal" SIZE="8" onChange='Calculate();' READONLY></td></tr>
<tr width='100%' height='50'><td align='center' width='20%'></td><td align='center' width='10%'></td><td align='center' width='20%'></td><td align='center' width='10%'></td><td align='center' width='10%'></td><td align='center' width='10%'></td><td align='center' width='20%'>
Shipping: <INPUT TYPE="TEXT" value="1.80" NAME="shipping" SIZE="8" onChange='Calculate();'>
<br>Tax 1: <INPUT TYPE="TEXT" value="0.90" NAME="tax1" SIZE="8" onChange='Calculate();'>
<br>Tax 2: <INPUT TYPE="TEXT" value="1.42" NAME="tax2" SIZE="8" onChange='Calculate();'>
<br>Tax 3: <INPUT TYPE="TEXT" value="0.61"NAME="tax3" SIZE="8" onChange='Calculate();'>
<br>Total: <INPUT TYPE="TEXT" NAME="total" SIZE="8" onChange='Calculate();'></td></tr>
</table>
</form>

 

[Psycho]

I forget why this happens, but just add a toFixed() to the result to get the correct value. Updated function:

function Calculate()
{
    with(document.forms['myform'].elements)
    {
        var subTotal = parseFloat(Qty1.value) * parseFloat(Price1.value);
        Cost1.value = subTotal;
        subtotal.value = subTotal;

        var totalValue = parseFloat(subtotal.value) + parseFloat(shipping.value) + parseFloat(tax1.value)
                       + parseFloat(tax2.value) + parseFloat(tax3.value);
        total.value =  totalValue.toFixed(2);
    }
    return;
}

[Psycho]

This page describes the problem in better detail, but the solutioin is the same as I provided.

 

http://blog.unidev.com/index.php/2008/10/10/math-error-in-javascript/

[M.O.S. Studios]

works 100% thanks!