Errro with DOM

[brunopeople]

Good day pal!!

i have been trying to execute your example just for learning. So i had encountered this problem with this error.

"Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('file://') does not match the recipient window's origin ('null')." and I don´t know this is happening?? if you could help to solve this problem, I much appreciate.

here my repositories:

https://github.com/brunopeople/Teste-Icasei