带Laravel 5.6的Ajax Post

我不知道如何让这个Ajax请求发布。

     <button class="btn btn-sm btn-primary" id="ajaxSubmit">Submit</button>

      <textarea rows="4" class="form-control resize_vertical" id="application_notes" name="application_notes" placeholder="Notes">{{$application->notes}}</textarea>



<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
  var url = "/instructor-notes-save/{{$application->id}}"
      $(document).ready(function(){
         $('#ajaxSubmit').click(function(e){
               e.preventDefault();
               $.ajaxSetup({
                  headers: {
                      'X-CSRF-TOKEN': $('meta[name="_token"]').attr('content')
                  }
              });
            $.ajax({

                  url: url,
                  method: 'post',
                  data: {
                     application_notes: jQuery('#application_notes').val(),
                  },
                  success: function(response){
                     console.log(response);
                  }});
               });
            });
</script>

我的控制器是:

public function saveNotes(Request $request, $id)
    {
      $application = Application::findOrFail($id);
      $application->notes = $request->application_notes;
      $application->save();
      return response()->json(['success'=>'Data is successfully added']);
    }

值得一提的是,我的路线是:

Route::post('/instructor-notes-save/{id}', 'InstructorsController@saveNotes')->name('instructor.save.note');

要使这个Ajax请求工作,我缺少什么?在控制台日志中,我得到一个419未知状态错误。