如何使用javascript获取此集合的总计数ID？

Question

I have this collection: https://graph.facebook.com/2playcz/albums

This collection contains 8 id. How can i get the total count id of this collection using javascript? ( Total = 8 )

Source:

  {
       "data": [
          {
             "id": "201936779932071",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Tr\u00e9ninky",
             "link": "https://www.facebook.com/album.php?fbid=201936779932071&id=190320081093741&aid=41883",
             "cover_photo": "201937046598711",
             "count": 8,
             "type": "normal",
             "created_time": "2012-07-02T09:33:43+0000",
             "updated_time": "2012-09-15T12:05:44+0000",
             "can_upload": false,
             "likes": {
                "data": [
                   {
                      "id": "1788805921",
                      "name": "Edita Nov\u00e1"
                   },
                   {
                      "id": "100001449904219",
                      "name": "Mirka Brani\u0161ov\u00e1"
                   }
                ],
                "paging": {
                   "next": "https://graph.facebook.com/201936779932071/likes?limit=25&offset=25&__after_id=100001449904219"
                }
             }
          },
          {
             "id": "205206429605106",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Turnaje a akce",
             "link": "https://www.facebook.com/album.php?fbid=205206429605106&id=190320081093741&aid=42900",
             "cover_photo": "205208716271544",
             "count": 14,
             "type": "normal",
             "created_time": "2012-07-10T19:36:53+0000",
             "updated_time": "2012-09-15T12:04:05+0000",
             "can_upload": false
          },
          {
             "id": "221784994613916",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Tenisova \u0161kolka 2play",
             "description": "Tenisov\u00e1 \u0161kolka 2play",
             "link": "https://www.facebook.com/album.php?fbid=221784994613916&id=190320081093741&aid=49379",
             "cover_photo": "221785024613913",
             "count": 9,
             "type": "normal",
             "created_time": "2012-08-31T11:19:59+0000",
             "updated_time": "2012-09-14T15:17:53+0000",
             "can_upload": false
          },
          {
             "id": "203405996451816",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Webov\u00e9 fotografie - Logo",
             "link": "https://www.facebook.com/album.php?fbid=203405996451816&id=190320081093741&aid=42285",
             "cover_photo": "203406586451757",
             "count": 11,
             "type": "normal",
             "created_time": "2012-07-05T10:12:40+0000",
             "updated_time": "2012-09-14T15:16:40+0000",
             "can_upload": false
          },
          {
             "id": "190332361092513",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Cover Photos",
             "link": "https://www.facebook.com/album.php?fbid=190332361092513&id=190320081093741&aid=39232",
             "cover_photo": "225939404198475",
             "count": 2,
             "type": "normal",
             "created_time": "2012-06-09T13:52:38+0000",
             "updated_time": "2012-09-12T18:15:51+0000",
             "can_upload": false
          },
          {
             "id": "190802884378794",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Wall Photos",
             "link": "https://www.facebook.com/album.php?fbid=190802884378794&id=190320081093741&aid=39324",
             "cover_photo": "190802891045460",
             "count": 2,
             "type": "wall",
             "created_time": "2012-06-10T13:19:48+0000",
             "updated_time": "2012-07-17T17:16:19+0000",
             "can_upload": false
          },
          {
             "id": "205207126271703",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Ostatn\u00ed",
             "link": "https://www.facebook.com/album.php?fbid=205207126271703&id=190320081093741&aid=42902",
             "cover_photo": "205209679604781",
             "count": 4,
             "type": "normal",
             "created_time": "2012-07-10T19:40:05+0000",
             "updated_time": "2012-07-16T14:47:16+0000",
             "can_upload": false,
             "likes": {
                "data": [
                   {
                      "id": "100001449904219",
                      "name": "Mirka Brani\u0161ov\u00e1"
                   }
                ],
                "paging": {
                   "next": "https://graph.facebook.com/205207126271703/likes?limit=25&offset=25&__after_id=100001449904219"
                }
             }
          },
          {
             "id": "190320914426991",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Profile Pictures",
             "link": "https://www.facebook.com/album.php?fbid=190320914426991&id=190320081093741&aid=39224",
             "cover_photo": "190327474426335",
             "count": 1,
             "type": "profile",
             "created_time": "2012-06-09T13:29:16+0000",
             "updated_time": "2012-06-09T13:43:08+0000",
             "can_upload": false
          },
          {
             "id": "190322704426812",
             "from": {
                "name": "2play.cz - Tenisov\u00e1 \u0161kola",
                "category": "Sports league",
                "id": "190320081093741"
             },
             "name": "Logo",
             "description": "Loga spole\u010dnosti",
             "link": "https://www.facebook.com/album.php?fbid=190322704426812&id=190320081093741&aid=39225",
             "type": "normal",
             "created_time": "2012-06-09T13:34:09+0000",
             "updated_time": "2012-07-05T10:16:58+0000",
             "can_upload": false
          }
       ]
    }

Answer 1

如果您指的是data数组中的项目数， data.length 。

Answer 2

First of all, there 9 ids. If you want to count the number of elements in array there's a built-in property length . So that if your object is called x you retrieve the length of data by accessing x.data.length .

On the other hand, if you wanted to count the number of unique ids (IDs should by unique anyway, but if you really really wanted to) you have to manually iterate through the array and count them:

var countIds = function (arr) {
    var uniqueIds = {}, num = 0;
    if (!arr.data) return false;
    arr.data.forEach(function (val, i) {
      if (typeof uniqueIds[val.id] === "undefined") {
        ++num;
        uniqueIds[val.id] = true;
      }
    });
    return num;
};