How to create a confirmation screen inside jestor custom pages

@sfernandes has asked:

I’m creating a custom page, I’d like to when I click on a button to check out the stock, it opens a small screen with a confirmation message and a confirm button.

How do I do this in the jestor? Would I have to create another custom page and make an iframe? Is there any tutorial or example I can follow to do something like this?

@sfernandes you can use javascript confirm for that. It’s available in all browsers Window API: confirm | Can I use... Support tables for HTML5, CSS3, etc

const ok = window.confirm('are you sure?')