I have been working on Magento 1.9.2.4, I am using an ajax cart extension to adding the product to cart, and its working good. the only problem I am having is once we click add to cart button is adding the product to cart, and if we click the button twice and so on the product keeps adding to the cart or quantity of the item in cart increases on every click on "add to cart" button,
I think it's Magento's default functionality, And I am trying to show a dialogue stating this product is already in the cart'* when the product is already added before in the cart while clicking on the "add to cart" button.
Any ideas for the function are welcomed.