I wanted to have a mostly pure JS solution to eliminate possible other problems in your object wrapper.

And XHR is not the only possibility to fetch data, FF has even a fetch function, and emscript offers a wget method.

Having a browser compatibility switch inside JS to fix incompatibilities is the approach I'm used to, i.e. xfetch could adapt to various contexts.

I tried to design my code as flexible as possible, feel free to patch functions according to your needs. :)