Thanks its working now.
Can you please guide me on or theme function available on the following querry:

I’m looking for my woocommerce store that adds a product to the cart when quantity is changed without clicking add to cart.

Example:
A customer is in the shop page (product archive) he wants 5 cups, by default the quantity field should be 0. Then the customer types 5 in the quantity field without clicking “add to cart” there should automatically be 5 cups in the cart.

When the customer changes his mind and wants 3 cups he can go back, and type 3 instead of 5 in the quantity field without clicking “add to cart” and he should now have 3 cups in his cart

Basically syncing the quantity field with the cart.