So, here is one thing you have to keep in mind:
The same-origin-policy for networking.
http://hyperhh.de/html5/testFetch-9.0.0-dp-7X.html
works with loading images but this one fails:
http://hyperhh.org/html5/testFetch-9.0.0-dp-7X.html
There is no other difference but using .org instead of .de
Both point to identic files (files to load have relative paths).