Specifying multiple targetOrigin uris in postmessage

Unfortunately you can't. You should either provide "*" or single specified domain.

You could try to send multiples time, one per domain:

targetWindow.postMessage(message, "https://domain1.com");
targetWindow.postMessage(message, "http://localhost");

⚠ It is not recommended use "*" to prevent security vulnerabilities.

You can also make an array + loop