[whatwg] using postMessage() to send to a newly-created window

Darin Fisher darin at chromium.org
Tue Jan 5 17:00:11 PST 2010

The window doesn't open synchronously, so you should have to wait for
http://x/ to load (or for its document to at least be created) before you
can start communicating with it.

Note: If you instead open "about:blank" you should be able to communicate
with it synchronously since "about:blank" is loaded synchronously.  It is

>From the newly opened window, you could try posting a message to its opener.
 The opener could then handle that event and use it as a signal to know that
it can know begin communicating with the newly opened window.

I haven't tested any of this ;-)


On Mon, Dec 21, 2009 at 7:24 PM, Dirk Pranke <dpranke at chromium.org> wrote:

> Hi all,
> In the course of testing something today, I attempted to create a
> window and immediately post a message to it, and was surprised that it
> didn't seem to work.
> E.g.:
> var w = window.open("http://x");
> w.postMessage("hello, world", "*");
> w never got the message - this seemed to be consistent across Safari,
> Chrome, and FF (all I had installed on my Mac at the time, so
> apologies to Opera, IE, and anyone else I've left out).
> Is this supposed to work? If not, is there a reliable way for the the
> source to know when it is safe to send a message to the target? The
> only way I can think of is for the target to send a message back to
> the source, which only works if the target can get a reference to the
> source using window.opener, which may or may not be possible or
> desirable ...
> If this isn't supposed to work, can we state this explicitly in the spec?
> -- dirk
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