Ciao a tutti,
vorrei riuscite a calcolare la percentuale di sconto su una somma di prodotti da selezionare.
Qualcuno può aiutarmi? Qui link
https://jsfiddle.net/0kang3rr/


codice HTML:
<table width="910" cellpadding="0" cellspacing="0">  <col width="105">  <col width="57">  <col width="234">  <col width="46" span="9">  <tr>    <td>Name</td>    <td>&nbsp;</td>    <td>Version</td>    <td>Type</td>    <td>&nbsp;</td>    </tr>  <tr>    <td>Prod 1</td>    <td>&nbsp;</td>    <td>1 a</td>    <td><input type="checkbox" class="tot_amount" value="10" id="filled-in-box1" onclick="chaked1();">      10</td>    <td>&nbsp;</td>  </tr>  <tr>    <td></td>    <td>&nbsp;</td>    <td>1 b</td>    <td><input type="checkbox" class="tot_amount" value="20" id="filled-in-box1" onclick="chaked1();">      20</td>    <td>&nbsp;</td>    </tr>  <tr>    <td></td>    <td>&nbsp;</td>    <td>1 c</td>    <td><input type="checkbox" class="tot_amount" value="30" id="filled-in-box1" onclick="chaked1();">      30</td>    <td>&nbsp;</td>    </tr>  <tr>        </tr>        <tr>    <td>Total      <input type="text" id="cost" readonly>    </td>  </tr>  <tr>    <td width="98">Taxes</td>    <td width="115">Discount</td>    <td width="118">Default price</td>  </tr>  <tr>    <td><select class="select" name="taxes" onChange="updateInput()">      <option value="no" selected>no taxes</option>      <option value="19">19% taxes</option> <!-- <====================== -->    </select></td>    <td><select class="select" name="discount" onChange="updateInput()">        <option value="0" selected>0% discount</option>      <option value="5">5% discount</option>      <option value="10">10% discount</option>      <option value="20">20% discount</option>    </select></td>    <td><input type="text" class="select" name="cost" id="cost" value="1000"></td>  </tr>  <tr>    <td>Price after discount</td>    <td>Taxes</td>    <td>&nbsp;</td>  </tr>  <tr>    <td><input type="text" name="price" value="2000"></td>    <td><input type="text" name="ttaxes" value="0"></td> <!-- <====================== -->  </tr></table>
codice:
<script>    function chaked1(){
    $("#filled-in-box1").click(function(event)
    {
    if(this.checked)
    {
    document.getElementById("one").value=document.getElementById("filled-in-box1").value;
    document.getElementById('one').readOnly = false;
    }
    else
    {
    document.getElementById("one").value="0";
    document.getElementById('one').readOnly = true;
    }


    });
    }
    </script>


    <script>
    function chaked2(){
    $("#filled-in-box2").click(function(event)
    {
    if(this.checked)
    {
    document.getElementById("two").value=document.getElementById("filled-in-box2").value;
    document.getElementById('two').readOnly = false;
    }
    else
    {
    document.getElementById("two").value="0";
    document.getElementById('two').readOnly = true;
    }
    });


    }
    </script>




    <script>
    $(".tot_amount").click(function(event) {
    var total = 0;
    $(".tot_amount:checked").each(function() 
    {
    total += parseInt($(this).val());
    });


    if (total == 0) {
    $('#cost').val('');
    }
    else {
    $('#cost').val(total);
    }
    });




function updateInput(){
    var discount = document.getElementsByName("discount")[0].value;
    var cost = document.getElementsByName("cost")[0].value;
    document.getElementsByName("price")[0].value = cost - (cost * (discount / 100));


    var taxes = document.getElementsByName("taxes")[0].value; // <======================
    if ( isNaN( taxes ) ) // IF "no taxes" IS SELECTED...
         document.getElementsByName("ttaxes")[0].value = 0;
    else { cost = document.getElementsByName("price")[0].value;
           document.getElementsByName("ttaxes")[0].value = (cost * (taxes / 100));
         }
}
</script>