Auto Sum Transaksi POS

Assalamualaikum,.. 
<script type="text/javascript">
$(document).ready(function() {
  update();
  $(".quant").change(function() {
    //this: context of the input that was changed
    $.get(
      'media.php?module=keranjangbelanja&stat=1&AddTocart', {
        id: $(this).attr('data-id'),
        returnUrl: '',
        quantity: $(this).val()
      });
    update();
  });
 
  function update() {
    var sum = 0.0;
    var quantity;
    $('#myTable > tbody  > tr').each(function() {
      quantity = $(this).find('.quant').val();
      var price = parseFloat($(this).find('.price').attr('data-price').replace(',', '.'));
      var amount = (quantity * price);
 
      sum += amount;
      $(this).find('.amount').text('' + amount);
    });
    $('.total').val(sum);
  }
});
</script>