Given a window of an iframe, is there easy access to the owning iframe?
<p>I've been playing around with <em>postMessage</em> just to have a better understanding of how it works, with the following example:</p>

<p><a href="http://hashcollision.org/tmp/hello-iframe.html" rel="nofollow">http://hashcollision.org/tmp/hello-iframe.html</a></p>

<p>It's slightly elaborate: for each character in the message, this constructs an iframe sourced to <a href="http://hashcollision.org/tmp/hello-iframe-inner.html" rel="nofollow">http://hashcollision.org/tmp/hello-iframe-inner.html</a>.  I then use postMessage to communicate to each individual iframe, telling it what character to show.  Also, the iframes communicate the geometry of the iframe back to the parent page via postMessage too.  It's all quite useless, but it's a cute test page.</p>

<p>One of the things that's currently awkward is, given the window of an iframe, to find the owning iframe.</p>

<p>I'm doing a <em>for</em> loop to walk all my iframes and check the window with <em>===</em>, but that seems a bit silly.  Are there better ways to do this?</p>
