JavaScript 判断 Undefined 类型

1 var cookiestr = '';
2     chrome.cookies.getAll(
3         {
4             'url': 'https://mp.weixin.qq.com',
5             'secure': true
6         }, function (cookies) {
7             for (var i in cookies) {
8                 if (typeof (i.name) != 'undefined' && typeof (i.value) != 'undefined') {
9                     cookiestr += i.name + '=' + i.value + ';';
10                 }
11             }
12             alert(cookiestr);
13
14     });