嘗試訪問json對象時出現'找不到變量'錯誤

Question

希望有人能幫助我。下面的JS，加載一個JSON文件並將這些縣分析到一個選擇菜單中。它也刪除重複項。現在在JSON飼料，每個項目都有這樣的事情：

{ 
    "County":"Antrim", 
    "Town":"Antrim Town", 
    "Restaurant":"Diane's Restaurant & Pizzeria" 
} 

我所試圖做的是在第一選擇菜單，一旦用戶選擇了縣委，第二選擇菜單與來自值更新兒子對象。目前，我得到一個'無法找到變量'的錯誤，我無法解決原因。由於某種原因數據數組不可用？

<script type="text/JavaScript"> 
    $(document).ready(function(){ 
    //get a reference to the select elements 
    var county = $('#county'); 
    var town = $('#town'); 
    var restaurant = $('#restaurant'); 

    //request the JSON data and parse into the select element 
    $.getJSON('rai.json', function(data){ 
     console.log(data); 

     //clear the current content of the select 
     $('#county').html(''); 
     $('#county').append('<option>Please select county</option>'); 

     $('#county').html(''); 
     $('#town').append('<option>Please select town</option>'); 

     $('#restaurant').html(''); 
     $('#restaurant').append('<option>Please select restaurant</option>'); 

     //iterate over the data and append a select option 
     $.each(data.irishtowns, function(key, val) { 
      county.append('<option id="' + val.County + '">' + val.County+ '</option>'); 
     }); 

     var a = new Array(); 
     $('#county').children("option").each(function(x){ 
      test = false; 
      b = a[x] = $(this).text(); 
      for (i=0;i<a.length-1;i++){ 
       if (b ==a[i]) test =true; 
      } 
      if (test) $(this).remove(); 
     }); 
    }); 

    $("#county").change(function() { 
     var myCounty = $(this).val(); 
     console.log(myCounty); 
     $.each(data.irishtowns, function(key, val) { 
      if (val.Town === myCounty) { 
       town.append('<option id="' + val.Town + '">' + val.Town + '</option>'); 
      } 
     }); 
    }); 
}); 
</script> 

Answer 1

數據不在範圍內這一行

$.each(data.irishtowns, function(key, val) { 

您可以移動此成回調，或使用全局變量來提供訪問：即回調有一個線countries = data然後

$.each(countries.irishtowns, function(key, val) {