Hey guys
I have some problem for counting (products) in cart dynamically with ajax when clicking on (add to cart) "button":
for example: consider that there's only one product in cart, user clicks (add to cart) "button", show div with message added plus count products in cart dynmically

Here's my php code (counter of products in cart):

<span class="products-in-cart">
( <?= isset($cart_id) ? $cartObj->countProductsInCartByCartId($cart_id) : "0" ?> )
</span>

and here's jquery code (ajax):

$(document).ready(function () {
    var addToCart = $('input[name=addToCart]');
    addToCart.on('click', function () {
    var productId = $(this).parent().find('input[name=productId]').val();
    var data = {
    productId: productId,
    addToCart: true
    };
    var url = "addToCart.php";
    $.post(url, data, function () {
    var div = $("<div></div>");
    div.addClass('addedToCart'); $("body").append(div.hide().text("added").fadeIn(500).delay(1000).fadeOut(500));
    var speed = 500;
    $("body").append(div.css('display','none').text("added").css({'display':'block', 'opacity':'0'}).animate({'opacity':'1'}, speed).delay(1000).animate({'opacity':'0'}, speed,function(){
    $(this).remove();
    }));
    });

    });

    $('form.cartOperations').submit(function () {
    return false;
    });
});

if your trying to set a number to show how many items are in the cart currently
whatever your holder is i would replace that with the current count some where in your post so you add the item and update

$("#current_items_count").text(current_count);

// or get the previous number and add one 

var current_count = parseInt($("#current_items_count").text());
$("#current_items_count").text(current_count + 1);