<!DOCTYPE HTML> <html> <head><meta charset='utf-8'></head> <body> <b>Sub Frame 2</b><br/> <script type='application/javascript'> // make sure to set document.domain to same domain as frame 1 window.onload = function() { document.domain = "mochi.test"; // let Frame 1 know that we are ready to run the test window.parent.parent.frames[0].postMessage({start: "startTest"}, "*"); }; </script> </body> </html>