How do I create a cart that is present as a sidebar on all pages of the cart process

[FZeus]

How do I create a cart that is present as a sidebar on all pages of the cart process ? When I add or remove an addon, I want it to remove or add it in real time without having to refresh the page. Choose domain > Addons (confdomains) > Checkout

Like the one from ajax cart from ractstudio but it's 2-3 years old and deprecated, and not updated in ages, is is still good though ? One from whmcsglobalservices has a lot of bugs.

 

Urgent please 

[FZeus]

Is there no one here to answer please ? For example on the standard_cart template  on the configure products stage there is a cart present on the left and when you change the billing from monthly, yearly etc it changes in real time, without having to refresh the page. How can I do the same thing but for the configure domains (confdomains) step ?