var UrlQueryString = function (query) {
    // This function is anonymous, is executed immediately and 
    // the return value is assigned to QueryString!
    var query_string = {};

    if (query == undefined || query == "")
        query = window.location.search.substring(1);
    else {
        var i = query.indexOf("?");
        if (i > 0) {
            query = query.substring(i+1);
        }
    }

    var vars = query.split("&");
    for (var i = 0; i < vars.length; i++) {
        var pair = vars[i].split("=");
        // If first entry with this name
        var key=pair[0], value;

        if (typeof query_string[pair[0]] === "undefined") {
            value = decodeURI(pair[1]);
            // If second entry with this name
        } else if (typeof query_string[pair[0]] === "string") {
            var arr = [query_string[pair[0]], pair[1]];
            value = decodeURI(arr);
            // If third or later entry with this name
        } else {
            value = decodeURI(pair[1]);
        }

        query_string[key] = value;
        this[key] = value;
    }

    this.get = function (key) {
        if (query_string[key] != undefined) {
            return query_string[key];
        } else {
            //support friendly URL.
            var query2 = window.location.href;
            var vars = query2.split("/");
            for (var i = 0; i < vars.length; i++) {
                var reg = new RegExp("" + key + "([.]*[^\/]+)", "g");
                result = reg.exec(vars[i]);
                if (result != null && result.length == 2) {
                    return result[1];
                }
            }
        }
    };
    return this;
};

var QueryString = new UrlQueryString();