Execute custom javascript code when a survey "appears"

Hi,

i am using a popover which displays on exit intent. What i try to do is do make the background slightly grey in order to focus the survey. Since there is no default option at all to select something simple and common like this i am looking for a way to execute javascript code when the survey shows up. Is there any option and where will this code be located: in the frame und another domain or surrounding the iframe on my domain?

thank you in advance

Michael