How to make JS execute only when there is an open site?

Question

JavaScript

There is a site A with a script , and site B (this is google.com)

We need the script on site A to be executed ONLY IF site B is OPEN .

If the user has closed site B, the script stops running. Opened site B again - the script on site A continues to work.

Give me a direction, I'll figure it out on my own. Thanks everyone

Answer 1

If the second site opened the first one, then you can track its status from the first site. See the site property below.
site = window.open('https://google.com');