Untitled

<html>
<head>
  <script type="text/javascript" src="jquery.js"></script>
</head>
<body>
<form class="formProduct" id="formProduct" action="#" method="post">
<input type="text" name="quantity" id="formProductQuantity" value="{{ product.stock.minimum }}" /> // text field with quantity
<a class="button blue opener" href="" title="{{ 'Add to cart' | t }}"><span>Add to cart</span></a> // submit button
</form>
</body>
</html>
<script type="text/javascript">
 var addUrl = "http://shop.com/cart/add/123456/?quantity="; // 123456 is the product id

jQuery(document).ready(function(){
asset("#formProduct");
});
function asset(product){

    jQuery(product + " input#formProductQuantity").val("1");
    jQuery(product + " #formProductQuantity").keyup(function () {
         var val = jQuery(product + " input#formProductQuantity").first().val();
    });

    jQuery(product + " .opener").click(function() {
           var val = jQuery(product + " input#formProductQuantity").first().val();

              // Go to page
              window.location.href = addUrl + val;

              return false;

    });
 }
 </script>