function getURL(uri) {
uri.dir = location.href.substring(0, location.href.lastIndexOf('\/'));
uri.dom = uri.dir; if (uri.dom.substr(0,7) == 'http:\/\/') uri.dom = uri.dom.substr(7);
uri.path = ''; var pos = uri.dom.indexOf('\/'); if (pos > -1) {uri.path = uri.dom.substr(pos+1); uri.dom = uri.dom.substr(0,pos);}
uri.page = location.href.substring(uri.dir.length+1, location.href.length+1);
pos = uri.page.indexOf('?');if (pos > -1) {uri.page = uri.page.substring(0, pos);}
pos = uri.page.indexOf('#');if (pos > -1) {uri.page = uri.page.substring(0, pos);}
uri.ext = ''; pos = uri.page.indexOf('.');if (pos > -1) {uri.ext =uri.page.substring(pos+1); uri.page = uri.page.substr(0,pos);}
uri.file = uri.page;
if (uri.ext != '') uri.file += '.' + uri.ext;
if (uri.file == '') uri.page = 'index';
uri.args = location.search.substr(1).split("?");
return uri;
}
var uri = new Object();
getURL(uri)

(c) copyright Stephen Chapman, 1st Jan 2005.
Example:
alert('http://'+uri.dom+uri.path+'/folder/file.js');

getURL: Current Page Reference

url, page

JavaScript