Json格式转string

function Serialize(obj) {
            switch (obj.constructor) {
                case Object:
                    var str = "{";
                    for (var o in obj) {
                        str += "\""+o + "\":" + Serialize(obj[o]) + ",";
                    }
                    if (str.substr(str.length - 1) == ",")
                        str = str.substr(0, str.length - 1);
                    return str + "}";
                    break;
                case Array:
                    var str = "[";
                    for (var o in obj) {
                        str += Serialize(obj[o]) + ",";
                    }
                    if (str.substr(str.length - 1) == ",")
                        str = str.substr(0, str.length - 1);
                    return str + "]";
                    break;
                case Boolean:
                    return "\"" + obj.toString() + "\"";
                    break;
                case Date:
                    return "\"" + obj.toString() + "\"";
                    break;
                case Function:
                    break;
                case Number:
                    return "\"" + obj.toString() + "\"";
                    break;
                case String:

                    return "\"" + obj.toString() + "\"";
                    break;
            }

        }