I am loading an iFrame of a different domain. Both the parent and the iFrame sites are under my control. I\'m using iFrame.postMessage to post messages to the iFrame. The si
I am not sure how are you catching the postMessage on the parent window or even catching or not, but below is the code that you should have on the parent window to catch the postMessage from the child iframe-
UPDATE:
I replicated your scenario at my end and found that you should use-
document.cookie.split(';');
parent.postMessage(clientId,"https://localhost:9443/oauth2/loginstatus");
instead of-
opIFrame.cookie.split(';');
opIFrame.postMessage(clientId,"https://localhost:9443/oauth2/loginstatus");
Full Code
Parent Window: - http://localhost:8541
Parent Window
iFrame Page: - http://localhost:50761
iFrame Window
In the above code you can see I am accessing the cookie value in cross domain environment i.e. parent window is running on different domain and page loading in iframe is running on different domain.
I created a test cookie with test data in it and passed to the parent window using postMessage.