johnjbarton/q-comm — comment on commit 80a4447a74e0e8dbbc881fde8174cc72e1f30331
File: q-comm.js line 369
By kriskowal:

The origin parameter is for communicating between same-origin iframes. The notion is that the origin can change when the user navigates within the frame, so you have to explicitly say the origin you intend to receive the message and it will be discarded otherwise.