More precise and cross-browser async method through postMessage

[Panya]

No description provided.

[wycats]

In at least one browser (IE8), postMessage is synchronous. I would like to use mutation observers if available, otherwise test for broken postMessage, otherwise use setTimeout. Want to update your patch with that strategy?

[Panya]

Yes. But I don't know any other browsers with synchronous postMessage.

[wycats]

@Panya Sure, but having rsvp.js fail to behave correctly in IE8 is a non-starter.

[Panya]

postMessageSupport returns false for IE8, because in IE8 document.documentMode <= 8.

[bengillies]

A better test would surely be something along the following lines:

function isPostMessageAsync() {
    var isAsync = true;

    if (!('postMessage' in window)) return false;

    function receiver() {
        isAsync = false;
    }

    window.addEventListener('message', receiver);
    window.postMessage(...);
    window.removeEventListener(receiver);

    return isAsync;
}

[tomdale]

@Panya Have you had a chance to take @bengillies suggestion into account?

[wagenet]

@wycats, @tomdale, it looks like all the suggested changes were taken into account. That said, it no longer merges cleanly. Is this something we should try to get working?

[stefanpenner]

i am open to these additions, but this PR has been stale for some time so I will close this issue until someone resurrects.

[stefanpenner]

Although this is closed, postMessage does not appear stable and should be avoided. see: cujojs/when#197