I have been stuck on this for hours.
I have a.html on http://example.com that contains an iframe with src to
b.html on http://subdomain.example.com. a.html has some JS code
to postMessage to the iframe.
The code to postMessage is simple:
iframe_window.postMessage('message', iframe_element.src)
But this way, Chrome throws an error:
Unable to post message to http://subdomain.example.com. Recipient has origin null.
I have also tried:
iframe_window.postMessage('message', 'http://subdomain.example.com')
But NO LUCK!
This is the ONLY WAY it works:
iframe_window.postMessage('message', '*')
But I have heard '*' is not good to use.
No problems in Firefox.