function selectlang(lang)
{    
    var url = ""+window.location;
    var replacement = "______lang";        
    url = url.replace(/lang=[^&]+/, replacement);
    
    if(url.indexOf(replacement) == -1)    
    {
        if(url.indexOf("?") > -1)
            url += "&" + replacement;
        else
            url += "?" + replacement;
    }
    
    url = url.replace(replacement, "lang=" + lang);    
    window.location = url;
}