var baseHref = "";
function getBase(){
     var baseTag = document.getElementsByTagName("base");
     for(var i=0; i<baseTag.length; i++){
          baseId = baseTag[i].id;
          baseHref = baseTag[i].href;
     }
}
getBase();
// if(baseHref=="") baseHref = 'http://'+location.host;