Your task is to implement a basic shopping cart for a website, following these basic rules:
- Store the cart on localStorage
- The cart should only know about item IDs and their quantity
- The cart should notify when it has been updated
- UI could be like flipkart cart, the functionality you should implement is add/remove items, increment/decrement item count and update localStorage on any change
- The UI should be clean
- Focus on the cart, other parts are just helpers
- Dummy data should be used for the cart items