+ // set or re-set "lang" URL parameter
+ function lang_url(lang) {
+ var query = location.search;
+ // no query parameters? done
+ if (!query) {
+ return "?lang=" + lang;
+ }
+
+ // parameter does not exists
+ if (!query.match(/[\?&]lang=/)) {
+ return query + "&lang=" + lang;
+ }
+
+ // replace existing parameter
+ query = query.replace(/\?lang=([^&#;]*)/, "?lang=" + lang);
+ query = query.replace(/\&lang=([^&#;]*)/, "&lang=" + lang);