跨域XHR / AJAX：可能的解决方法？

I just had an idea to make cross-domain AJAX calls, because so far they really are a PITA to deal with. This is a solution I haven't seen exposed anywhere on the web, so it might be (probably is) flawed/dangerous for some reason, which I can't seem to see now, so I'm turning to you to tell me if this is legit or not :I just had an idea to make cross-domain AJAX ca