将变量传递给 .html() 函数

Question

     <!-- The select drop down menu (works fine) -->
     <select id="select-event-type">
        <?php foreach ($this->events as $event) {
            echo "<option value='" .$event->event_id. "'>" .$event->event_title."</option>";
        }?>
     </select>

     <!-- The javascript, which is supposed to output something according to the chosen option in the select drop down -->
     <script>
          (function ($) {
              var events = <?php echo (count($this->events) > 0) ? json_encode($this->events) : "null"; ?>;
              $(document).ready(function() {
                  $('#select-event-type').change(function() {
                      if (events) {
                          var event = events[this.selectedIndex];
                          $('#event-details').html(event);
                      }
                  });
              });
          })($);
     </script>

 <!-- In this div the output will be displayed -->
<div id="event-details"></div>

事件变量未定义。

例如，如果我这样做：var event = 'hello' 它会按预期输出“你好”。

所以问题似乎出在这部分：events[this.selectedIndex];。我做错了什么？

我对此真的很陌生。非常感谢您的帮助！！

更新：
控制台输出（在 chrome 中）：

     <script>
          (function ($) {
              var events = JSON.parse({"1":{"event_id":"1","event_title":"event1","event_desc":"event1","event_location":"eventlocation","event_requirements":"event1","event_date":"2022-07-20 15:00:00"},"2":{"event_id":"2","event_title":"event2","event_desc":"event2","event_location":"eventlocation","event_requirements":"event2","event_date":"2015-04-20 15:00:00"},"3":{"event_id":"3","event_title":"event3","event_desc":"event3","event_location":"eventlocation","event_requirements":"event3","event_date":"2019-11-20 16:00:00"}});               $(document).ready(function() {
                    $('#select-event-type').change(function() {
             if (events) {
                 var event = events[$(this).selectedIndex];
                 $('#event-details').html(event);
              }
           });
        });

    </script>

JSON：

{
    "1": {
        "event_id": "1",
        "event_title": "event1",
        "event_desc": "event1",
        "event_location": "eventlocation",
        "event_requirements": "event1",
        "event_date": "2022-07-20 15:00:00"
    },
    "2": {
        "event_id": "2",
        "event_title": "event2",
        "event_desc": "event2",
        "event_location": "eventlocation",
        "event_requirements": "event2",
        "event_date": "2015-04-20 15:00:00"
    },
    "3": {
        "event_id": "3",
        "event_title": "event3",
        "event_desc": "event3",
        "event_location": "eventlocation",
        "event_requirements": "event3",
        "event_date": "2019-11-20 16:00:00"
    }
}

Answer 1

要获取select 元素的值，请使用this.value。从而改变：

var event = events[this.selectedIndex];

收件人：

var event = events[this.value];

但是，如果您的 json 是索引为 0,1,2,3,4 的数组，而不是选项值为 keys 的对象，那么您对 ​​this.selectedIndex 的使用是正确的。

更新：

根据发布的示例 JSON，正确的代码应该是：

var event = events[this.selectedIndex + 1].event_title;

特别说明

您可以使用以下任一方法获取所有事件数据：

var event = JSON.stringify( events[this.selectedIndex + 1] ); //gives you a string of everything

或者你可以构建你想要的样子：

var event = $('<div/>');
$.each( events[this.selectedIndex + 1], function(k,v) {
    event.append( $('<div/>',{text:k + ': ' + v}) );
});

Answer 2

有关访问selectedIndex 属性的jQuery 方式，请参见this answer。您的答案可能如下所示：

var event = events[$(this).prop("selectedIndex")];

Answer 3

首先，您不需要 2 个现成的实例。试试吧，如果不行请告诉我。

<script>
   $(document).ready(function() {
     var events = <?php echo (count($this->events) > 0) ? json_encode($this->events) : "null"; ?>;
      $('#select-event-type').change(function() {
         if (events) {
             var event = events[$(this).selectedIndex];
             $('#event-details').html(event);
          }
       });
    });

</script>

selectedIndex 是什么意思？