title: What's wrong in this JavaScript code? I get the extra content from server which I don't response
body: <p>I get the data with <code>"{"success":true}&lt;audio controls="controls" style="display: none;"&gt;&lt;/audio&gt;"</code>，and occuring exception in Chrome Console with <code>Uncaught SyntaxError: Unexpected identifier</code> .But the expectable data is <code>{"success":true}</code>。What's wrong here? Could anybody give me some help <br />
  I don't know where the code <code>&lt;audio controls="controls" style="display: none;"&gt;&lt;/audio&gt;</code> is from.The debug screenshot<a href="https://i.stack.imgur.com/ePUXe.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ePUXe.png" alt="enter image description here"></a></p>
  
  <pre><code>$changePdForm.form({
          url : '/action/change',
          onSubmit : function(){
              return $changePdForm.form('validate');
          },
          success : function(data){
              var data = eval('(' + data + ')'); // change the JSON string to javascript object
              if (data.success) {
                  $.messager.alert('Tips','success！');
                  closeDiv();
              } else {
                  $.messager.alert('Tips', data.result);
              }
          }
      });
  </code></pre>
  
  <p>The backend Code below</p>
  
  <pre><code>@RequestMapping(value = "/change", method = RequestMethod.POST)
  @ResponseBody
  public Map&lt;String, Object&gt;  change(UserChange userChange,HttpSession session, HttpServletRequest request,HttpServletResponse response) {
      Map&lt;String, Object&gt; result = new HashMap&lt;String, Object&gt;();
      try{
          if(userChange != null){
              logger.debug(Constants.LOG_DIVISION_LINE + "modify start！");
              userService.change(userChange.getId(), userChange.getNewPassword(), userChange.getConfirmPassword());
              logger.debug(Constants.LOG_DIVISION_LINE + "modify end！");
          }else{
              logger.debug(Constants.LOG_DIVISION_LINE + "the info of password is null！");
          }
          result.put("success", true);
      }catch(Exception e){
          logger.debug(Constants.LOG_DIVISION_LINE + e.getMessage());
          e.printStackTrace();
          result.put("success", false);
          result.put("result", e.getMessage());
      }
      return result;
  }
  </code></pre>