url query 对象拼接

const serialize = function(obj) {
            var ary = [];
            for (var p in obj)
                if (obj.hasOwnProperty(p) && obj[p]) {
                    ary.push(encodeURIComponent(p) + '=' + encodeURIComponent(obj[p]));
                }
            return ary.join('&');
        };