功能循環內的jquery函數

Question

嗨，我在移動應用程序，我有以下問題。

我想從表billbayments中的每個條形碼的表法案中選擇數據。

這裏是我的代碼

 t.executeSql('SELECT barcode, amount, receiptno FROM billpayments WHERE receiptno > 0', 
      [], function(t, resultcollect) { 
       len = resultcollect.rows.length; 

        for (i = 0; i < len; i += 1) { 
         row = resultcollect.rows.item(i); 
         t.executeSql('SELECT barcode, buildingcode, flatdescription FROM bill WHERE barcode = ?', 
          [row.barcode], function(t, collectaddress) { 
           mybill = collectaddress.rows.item(0); 
           list.append('' + mybill.buildingcode + ',' + mybill.flatdescription + ',' + row.receiptno + ',' + row.amount + '</br>'); 
         }); 


        } 
        tameio = tameio.toFixed(2); 
        list.append('<table border="1">' + items.join('\n') + itemspay.join('\n') + '</table><p>' + tameio + ''); 
      }); 

但在HTML追加我收到row.receiptno和row.amount所有條形碼的最後一個值...

請幫助我被困。

Answer 1

迭代過程中，row被一遍又一遍覆蓋。要解決此問題，請使用助手函數創建一個新範圍，其中row是局部變量：

function dummy(i) { 
    var row = resultcollect.rows.item(i);    // <-- Local variable 
    t.executeSql('SELECT barcode, buildingcode, flatdescription FROM bill WHERE barcode = ?', 
     [row.barcode], function(t, collectaddress) { 
      var mybill = collectaddress.rows.item(0); // <-- LOCAL variable! 
      list.append(mybill.buildingcode + ',' + mybill.flatdescription 
         + ',' + row.receiptno + ',' + row.amount + '</br>'); 
    }); 
} 
for (i = 0; i < len; i += 1) { 
    dummy(i); 
}