To run this test you will need to put this file and Default-port-frame-contents.html on a webserver and then point your browser to http://localhost/Default-port-frame.html. We cannot make this a LayoutTest because we don't want to mess with people's default ports. <br> <iframe src="http://localhost:80/resources/Default-port-frame-contents.html"> </iframe> <script> function test() { var result = typeof frames[0].testData != 'undefined'; alert(result ? 'Success' : 'Failed'); } </script> <input type="button" onclick="test()" value="Click Me To Test" ></input>