将 Select2 数组输出转换为字符串

Question

我正在尝试将 select2 数组转换为要在表单中使用的字符串。目前我的输出如下所示：

?source%5B%5D=x1&source%5B%5D=x2

我希望将其转换为以逗号分隔的字符串。我尝试使用'string = source.join()'，但我的字符串输出为空。

%5B%5D=x1&source%5B%5D=x2&string=

我想要得到的是这样的：

字符串%5B%5D=x1,x2

<form action="/action_page.php">    
   <select class="form-control select2" multiple="" id="source" name="source[]" style="width: 250px;">

      <optgroup label="Group1">
         <option>x1</option>
         <option>x2</option></optgroup>
         <optgroup label="Group2">
            <option>y1</option>
            <option>y2</option></optgroup>
         </select>
         <script type="text/javascript">
            $(".select2").select2({
            tags: true
            });
         </script>
         <script type="text/javascript">
         string = source.join()
         </script>
         <input type='hidden' name='string' ></input>
         <br><br>
         <input type="submit">
      </form>

Answer 1

我不知道这是否真的是你想要的，但这可以为你提供线索。

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.7/css/select2.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.7/js/select2.min.js"></script>

<form onsubmit="onFormSubmit()">

   <select class="form-control select2" multiple="" id="source" style="width: 250px;">
      <optgroup label="Group1">
         <option>x1</option>
         <option>x2</option>
       </optgroup>
       <optgroup label="Group2">
          <option>y1</option>
          <option>y2</option>
      </optgroup>
   </select>
   <script type="text/javascript">
      // Init Select2
      var mySelect = $(".select2").select2({
        tags: true
      });
      // On form submit
      var onFormSubmit = function(){
        // Get selected value (only if at least one selected)
        if (mySelect.val() !== null && mySelect.val().length > 0) {
            var selectedSource = "string=" + mySelect.val().join(',');
            alert(selectedSource);
        }
      }
   </script>
   <input type='hidden' name='string' />
   <br><br>
   <input type="submit" />

</form>