jQuery：调用$ .getJSON时填充数组的问题

Question

这是我在尝试创建新的CouchDB文档时使用的代码（参考CODE）。该文档包含一个或多个现有的CouchDB文档（历史记录跟踪）。新创建的doc的结果json（参考JSON）类似于：

JSON：
{
  "_id": "b3360050039389801524044daf1c963c",
  "_rev": "1-2a5da40ce9a191b4decc27411ec9a181",
   "hodoc_type": "INCOMMING DELIVERY NOTE",
   "user_from": "ANS USER",
   "status": "INSTALLED ON SITE",
   "category": "ASET",
   "location": "MTX SPARE",
   "doctype": "hodoc",
   "items": [
     {
       "serial_number": "310310007590",
       "status": "STORED IN WAREHOUSE",
       "doctype": "data",
       "supplier": "INTRACOM",
       "po": "0",
       "category": "SPARE PART",
       "user_out": "IGOR JURUKOV",
       "mac": "NULL",
       "eqtype": "IDU",
       "location": "MTX SPARE",
       "location_comment": "NULL",
       "date_in": "2011-05-06",
       "date_out": "2011-05-06",
       "prf": "0",
       "part_number": "Z00-404/63.01",
       "user_in": "KOTE JANAKIEVSKI",
       "bar_code": "0",
       "manufacturer": "INTRACOM",
       "rma": "NULL",
       "product_name": "PSU for IDR-SM"
     },
     {
       "serial_number": "310407016955",
       "status": "STORED IN WAREHOUSE",
       "doctype": "data",
       "supplier": "INTRACOM",
       "po": "0",
       "category": "SPARE PART",
       "user_out": "IGOR JURUKOV",
       "mac": "NULL",
       "eqtype": "IDU",
       "location": "MTX SPARE",
       "location_comment": "NULL",
       "date_in": "2011-05-06",
       "date_out": "2011-05-06",
       "prf": "0",
       "part_number": "Z00-404/63.02",
       "user_in": "KOTE JANAKIEVSKI",
       "bar_code": "0",
       "manufacturer": "INTRACOM",
       "rma": "NULL",
       "product_name": "PSU for IDR-SM"
     }
   ]
}

CODE：
var docids = new Array();
var items = new Array();
$('div#divitemsout').find('img.item-out-remove').each(function () {
  var id = $(this).attr('attrid');
  if (docids.indexOf(id) == -1) {
    docids.push(docid);
  }
  var item = new Object;
  $.getJSON('/whdb/' + id, function(data) {
    $.each(data, function(key, val) {
      if (key !== "_id" && key !== "_rev") {
        item[key] = val;
      }
    });
    // Check No.1
    //alert(item.manufacturer);
  });
  // Check No.2
  //alert(item.manufacturer);
  items.push(item);
  });

问题和问题是：当下面的线条检查No.2被注释时，生成的json文档的“items”部分是[]。当警报（item.manufacturer）下面的Check No.2被取消注释时，我收到内容为“undefined”的警报，但生成的json文档的“items”部分已正确设置，就像示例中的show一样。有什么建议吗？

Answer 1

问题在于时机。在Web服务器返回对您的请求的响应之前，不会调用传递给getJSON的函数。因此，在调用item后，不会立即定义getJSON。添加alert调用只会减慢速度，以便异步调用有时间完成。

尝试移动items.push(item)回调中的getJSON行。

修改

为了清楚起见，请尝试此操作（在Chrome或Firefox中打开Firebug，以便您拥有正确的console.log功能）：

var docids = new Array();
var items = new Array();
var waiting = 0;
$('div#divitemsout').find('img.item-out-remove').each(function () {
  var id = $(this).attr('attrid');
  if (docids.indexOf(id) == -1) {
    docids.push(docid);
  }
  var item = new Object;
  waiting++;
  $.getJSON('/whdb/' + id, function(data) {
    waiting--;
    $.each(data, function(key, val) {
      if (key !== "_id" && key !== "_rev") {
        item[key] = val;
      }
    });
    items.push(item);
    if(waiting == 0) {
      console.log('items:', items);
    }
  });
});