function addParamsToUrl(url, key, val) {
    if(!val) {
        return uri;
    }
    var re = new RegExp("([?&])" + key + "=.*?(&|$)", "i");
    var separator = url.indexOf(‘?‘) !== -1 ? "&" : "?";
    if (url.match(re)) {
        return url.replace(re, ‘$1‘ + key + "=" + val + ‘$2‘);
    }
    else {
        return url + separator + key + "=" + val;
    }
}