-Every time I click on "submit", it brings me straight back to top.
Yes that is what default functionality when submitting forms, it always repaints the dom so it causes a jump and page's top position is rendered.
-which creates a poor user experience because the user would have to scroll back down where he was browsing the products
To make a good user experience you can use ajax for this functionality, as you tagged jQuery in your question then you can try with jquery ajax:
$('form').submit(function(e){
e.preventDefault(); // stops the form submission
$.ajax({
url:$(this).attr('action'), // action attribute of form to send the values
type:$(this).attr('method'), // method used in the form
data:$(this).serialize(), // data to be sent to php
dataType:"text",
success:function(data){
alert(data); // you can alert the success message.
},
error:function(err){
console.log(err);
}
});
});
I have used a dataType:"text",
just assuming if you are going to echo "Added in the cart.";
kind of message from the php.