ko.components.register('add-to-cart-button', {
  viewModel: function(params) {
    this.item = params.item;
    this.cart = params.cart;
    this.addToCart = function() {
      var CartProduct = Shop.Models.CartProduct;
      var CartProductService = Shop.Services.CartProductService;
      var ProductService = Shop.Services.ProductService;

      var data = this.item;
      var tmpCart = this.cart();
      var n = tmpCart.length;
      var item = null;

      if(data.stock()<1) {
        return;
      }
      while(n--) {
        if (tmpCart[n].product.id() === data.id()) {
          item = tmpCart[n];
        }
      }
      if (item) {
        CartProductService.addUnit(item);
      } else {
        item = CartProduct(data,1);
        tmpCart.push(item);
        ProductService.decreaseStock(item.product);
      }
      this.cart(tmpCart...