JSON获取用户id's在嵌套数组中

如果你应用@Mike C的评论，你会得到这样的结果：

var formattedJson = JSON.parse(json);
    for (i=0;i<formattedJson.items.length;i++){
        console.log(formattedJson.items[i].user.id);
    }

formattedJson取决于您是将JSON作为字符串还是作为有效的JSON获得，如果是这样，您不需要使用JSON.parse，您可以直接访问它。

像这样：

var json = {  
   "current_page":1,
   "per_page":100,
   "total_entries":3,
   "items":[  
      {  
         "user":{  
            "id":12729498,
            "owner_id":51603,
            "full_name":"test1",
            "email":"test1",
            "login":"test1",
            "phone":null,
            "website":null,
            "created_at":"2016-05-16T14:56:24Z",
            "updated_at":"2016-05-17T18:23:35Z",
            "last_request_at":"2016-05-17T19:23:37Z",
            "external_user_id":null,
            "facebook_id":null,
            "twitter_id":null,
            "blob_id":null,
            "custom_data":null,
            "twitter_digits_id":null,
            "user_tags":null
         }
      },
      {  
         "user":{  
            "id":12768158,
            "owner_id":51603,
            "full_name":"test2",
            "email":"",
            "login":"test2",
            "phone":null,
            "website":null,
            "created_at":"2016-05-17T18:25:13Z",
            "updated_at":"2016-05-17T18:25:13Z",
            "last_request_at":null,
            "external_user_id":null,
            "facebook_id":null,
            "twitter_id":null,
            "blob_id":null,
            "custom_data":null,
            "twitter_digits_id":null,
            "user_tags":null
         }
      },
      {  
         "user":{  
            "id":12769692,
            "owner_id":51603,
            "full_name":"test3",
            "email":null,
            "login":"test3",
            "phone":null,
            "website":null,
            "created_at":"2016-05-17T19:22:55Z",
            "updated_at":"2016-05-17T19:22:55Z",
            "last_request_at":null,
            "external_user_id":null,
            "facebook_id":null,
            "twitter_id":null,
            "blob_id":null,
            "custom_data":null,
            "twitter_digits_id":null,
            "user_tags":null
         }
      }
   ]
};
var arr = [];
json.items.forEach(function(item) {
    arr.push(item.user.id);
});
console.log(arr);

演示：https://jsfiddle.net/59tahwc6/1/

这是我的解决方案，评论并进行了错误检查：

var x = '{"current_page":1, "per_page":100, "total_entries":3, "items":[{"user":{"id":12729498}},{"user":{"id":12768158}},{"user":{"id":12769692}}]}';
// Parse the JSON
var userListObj = JSON.parse(x);
// Check if any entries exist
if (typeof userListObj.items != 'undefined' && userListObj.items.length > 0)
{
    // Loop through each user
    for (var i in userListObj.items)
    {
        // Check if a user ID exists
        if (typeof userListObj.items[i].user.id != 'undefined')
        {
            // Output the user ID to the console
            console.log (userListObj.items[i].user.id);
        }
    }
}