url=document.location.pathname;
url=url.substr(0,trimPosition);
xhr.open(method.toUpperCase(),url,this.options.async,this.options.user,this.options.password);

GET /h.c7c27d/foo.js HTTP/1.1
Host: fo.exemple.com
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
Connection: close