Type a message in the box, and see it appear in the linked document inside the iframe. Then, save the document to somewhere on your local computer, reopen the document and see the same effect working-cross-domain
It should be noted that this demo follows the old specification, which put postMessage() on the Document interface, and not the Window interface. Please don't point to this as it being a normative test case for the specification. Opera's implementation of postMessage predates the WHATWG/HTML5 effort by a fair bit, and as such, this example is now mostly outdated.
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