update the amount value by button

hi currently i have developed my own website named www.eyeview.com. i want to update the hidden amount to my add product by clicking radio buttons. i have a five radio buttons with values of 100$ 150$ 200£ 175$ and 87$ but hidden amount value is 222

var totalAmount = 222.00; //Set from the database 
function updateAmount(var additionalCost) 
{ 
document.getElementById("finalamount").innerHTML = totalAmount开发者_开发问答 + additionalCost;
} 

var $amount= 

(‘#repair_total_amount’).html(“Total <span class="repair-finalamount-txt">&pound;&nbsp;”+ total_amount+”</span>”); 


                                                                                                               `$amount.text('£ 100');`
`$amount.text('£ 150');`
`$amount.text('£ 175');
`$amount.text('£ 87'); 
`$amount.text('£ 200');

i want to display the value on the product palce ie basket item. there is no response in my page ie nothing action after i clicked.

give me a correct code plz for updating the amount also i wanna to need the function for update

thanks in adv

Based on the fact you have tagged this post with jQuery, here is a clean jQuery solution that will work for you (just ensure you include the library of course):

<script type="text/javascript">
    var startAmount = 222.0;    
    var finalAmount = 0;
    $(document).ready(function() {
      $('.c').click(function() {
        $('.c:checked').each(function() {
          finalAmount = startAmount + parseFloat($(this).val());
        });

        $('#finalAmount').html('Final Amount: $' + finalAmount);
      });
    });
</script>

    <input name="cost" type="radio" value="100" class="c" /> 100$
    <input name="cost" type="radio" value="150" class="c" /> 150$
    <input name="cost" type="radio" value="200" class="c" /> 200$
    <input name="cost" type="radio" value="175" class="c" /> 175$
    <input name="cost" type="radio" value="87" class="c" /> 87$
    <br />
    <span id="finalAmount">Final Amount: $0</span>

document.getElementById('BUTTON-ID-HERE').onclick = function(){ updateAmount('VALUE HERE') }; 

Should be sufficent. Hope that helps.