How to catch form submit event (from iframe) in bitrix24?

Question

Bitrix24

1) Task - "there is a logic in the parent that shows the popup with the Bitrix24 form. If the form is submitted, the popup should be hidden and never shown again."
2) The form is created inside the iframe. How can the parent know that the form submit event has occurred?

Answer 1

as an option, you can use cookies, for example, if it is 0, then it has not been sent yet or something like that