[whatwg] Request: window.postMessage should be async

Anne van Kesteren annevk at opera.com
Fri Apr 4 15:11:52 PDT 2008

On Sat, 05 Apr 2008 00:03:58 +0200, Aaron Boodman <aa at google.com> wrote:
> On Fri, Apr 4, 2008 at 2:39 PM, Anne van Kesteren <annevk at opera.com>  
> wrote:
>> It doesn't make sense to change this given that all synthesized event
>> dispatching is synchronous. I don't think postMessage() should be  
>> different.
> It seems a little different to me. PostMesasge events are fired in
> another frame that the caller can't even see into. What difference
> does it make to the caller whether postMessage is synchronous or not?

This does not have to be any different for cross-frame events. The only  
difference is that cross-frame synthesized events don't work cross-origin.

> Furthermore, if we're going to add the ability for the conversation to
> go back and forth, to me it gets strange.

You need to the asynchronous coding for that case anyway. (Unless both  
parties know what they're going to say.)

> If you call postMessage() on a frame, and it returns the favor, you
> receive the reply before your call to postMessage() even returns. To
> me, the current shape of the API (and even the name 'post message')
> implies that this is an asynchronous system and that postMessage()
> returns immediately, queuing a message to be delivered to the other
> window.

Anne van Kesteren

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