Question

I have a form where users can create unlimited number of rows (using jquery- add new row) to add multiple products information. When they create new rows the code looks like following.

Now what I am trying to do is when every time an user puts the value of product quantity and product price I want to instantly calculate the total (product quantity* product price) and put the result in the total[] input and then adjust the total amount input which is at the bottom of the form.

I know how to do this when I have fixed amount of inputs using jquery, but since the amount of inputs are not fixed in this situation I have any idea on how to achieve this.

Could you please show me?

Thanks in Advance 🙂

 <tr>

   <td><input type="text" name="name[]" id="name_1" value=""></td>
   <td><input type="text" name="quantity[]" id="quantity_1" value=""></td>
   <td><input type="text" name="rate[]" id="rate_1" value=""></td>
   <td><input type="text" name="total[]" id="total_1" value=""></td>                        

 </tr>  

 <tr>

  <td><input type="text" name="name[]" id="name_2" value=""></td>
  <td><input type="text" name="quantity[]" id="quantity_2" value=""></td>
  <td><input type="text" name="rate[]" id="rate_2" value=""></td>
  <td><input type="text" name="total[]" id="total_2" value=""></td>                     

 </tr>  

   <!-- I have N number of rows like above. and at the bottom I have input for total -->
 <tr>

   <td>&nbsp;</td>
   <td>&nbsp;</td>
   <td>&nbsp;</td>
   <td><input type="text" name="totalamount" id="totalamount" value=""></td>                        

  </tr>                         

Answer 1

Here is one possible solution:

$(":text[name='quantity[]'], :text[name='rate[]']").on("change", function() {
    var totalamount = 0;
    $("tr").each(function() {
        var quantity = +$(this).find(":text[name='quantity[]']").val() || 0;
        var rate = +$(this).find(":text[name='rate[]']").val() || 0;
        var subtotal = quantity * rate;
        $(this).find(":text[name='total[]']").val(subtotal);
        totalamount += subtotal;
    });
    $("#totalamount").val(totalamount);
});​

DEMO: http://jsfiddle.net/ak49E/