When I have only one unit of the product and click on buy, the product page refresh, and not redirect to shopping cart. How to disable this function?
Form post:
<form id="addtocart_form" method="post" action="https://www.domain.com/checkout/cart/add/uenc/Z2VTcGVlZD1vZmYmX19fU0lEPVU,/product/15/form_key/hTmJMC7HS/">
Button:
<button type="button" title="Buy" id="product-addtocart-button" class="btn-cart" onclick="productAddToCartForm.submit(this)">BUY</button>
Change your setting from admin->configuration->sales>checkout under shopping cart. Set "After Adding a Product Redirect to Shopping Cart" to yes.