如何從AJAX讀取此JSON響應

Question

這是我對AJAX的回應

{"screen":[{"screen_name":"SCR1","screen_id":"1"},{"screen_name":"SCR2","screen_id":"2"},{"screen_name":"SCR3","screen_id":"3"},{"screen_name":"SCR4","screen_id":"4"},{"screen_name":"SCR5","screen_id":"5"},{"screen_name":"BIGSCR","screen_id":"6"}]}

success: function(response) {
    var jsondata = JSON.stringify(response);
    console.log(jsondata);
    var html = '';
    for (var i = 0; i < jsondata.screen.length; i++) {
        var screenName = jsondata.screen[i].screen_name;
        var screenId = jsondata.screen[i].screen_id;
        html += '<option value="' + screenName + '">' + screenId + '</option>';
    }
    $('#SCname').append(html);
}

但是我不斷

Uncaught TypeError：無法在for循環中讀取未定義的屬性“ length”

Answer 1

嘗試一下：有效。 像絲綢一樣光滑：（請參閱注釋以獲取解釋）

<select id="SCname"></select>
<script>
    $.ajax({
            dataType: 'json',
            //This JSON datatype returns a json encoded response
            url:"api/test.php",
            //This is the URL From where you fetch the JSON Data
            success: function(response){
                //Since the response array object has a single array element "screen", we make it myArray
                myArray = response["screen"];
                console.log(myArray);
                //We get six Objects in myArray.
                //Thsese are Arrays of your six screens . Now Using Loops
                var html = '';
                for (var i = 0; i < myArray.length; i++) {
                    // Each element is inside DOuble Array like: myArray[0]["screen_name"]
                    var screenName = myArray[i]["screen_name"];
                    var screenId = myArray[i]["screen_id"];
                    html += '<option value="' + screenName + '">' + screenId + '</option>';
                }
                $('#SCname').append(html);

                //Check your console ouput
                console.log(html);
            }  
      });
</script>

Answer 2

你不想stringify ，而是parse 。 更正它必須是：

var jsondata = JSON.parse(response);

但是請記住，jQuery可能已經為您解析了JSON。

Answer 3

JSON.stringify(object)返回一個字符串。 您需要一個JSON.parse(string) –返回一個對象。 另外，如果您的response 已經是一個object ，那么您根本就不必解析它：

success: function(jsonData) {
      var html = '';
      for (var i = 0; i < jsonData.screen.length; i++) {
          var screenName = jsonData.screen[i].screen_name;
          var screenId = jsonData.screen[i].screen_id;
          html += '<option value="' + screenName + '">' + screenId + '</option>';
      }
      $('#SCname').append(html);