Is cross-origin postMessage broken in IE10?

Question

I\'m trying to make a trivial postMessage example work...

• in IE10
• between windows/tabs (vs. iframes)
• across origins

Answer 1

I was mistaken when I originally posted this answer: it doesn't actually work in IE10. Apparently people have found this useful for other reasons so I'm leaving it up for posterity. Original answer below:

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Worth noting: the link in that answer you linked to states that postMessage isn't cross origin for separate windows in IE8 and IE9 -- however, it was also written in 2009, before IE10 came around. So I wouldn't take that as an indication that it's fixed in IE10.

As for postMessage itself, http://caniuse.com/#feat=x-doc-messaging notably indicates that it's still broken in IE10, which seems to match up with your demo. The caniuse page links to this article, which contains a very relevant quote:

Internet Explorer 8+ partially supports cross-document messaging: it currently works with iframes, but not new windows. Internet Explorer 10, however, will support MessageChannel. Firefox currently supports cross-document messaging, but not MessageChannel.

So your best bet is probably to have a MessageChannel based codepath, and fallback to postMessage if that doesn't exist. It won't get you IE8/IE9 support, but at least it'll work with IE10.

Docs on MessageChannel: http://msdn.microsoft.com/en-us/library/windows/apps/hh441303.aspx