سلام 

اینم  جواب تمرین

<script>
  $(document).ready(function()
  {
    $('#addbtn').click(function(e)
    {
      var input = $('#addinput');
      $.ajax
      ({
        url:'process/ajax-handler.php',
        method:'post',
        data: {action:"addFolder", Foldername:input.val()},
        success: function(data)
        {
          if (data=='1') 
          {
          var Folderid=data[0].id;
          var FolderName=data[0].Name;
          var folderRow = "<a href='?folder=id="+ Folderid+"'><i class='fa fa-folder'></i>"+FolderName+"</a>"+
          "<a class='remove' href='?Delete_folder"+ Folderid+"' >x</a>"
          $(folderRow).append('ul.folder_list');
          }else
          {
            alert(data); 
          }
        }
      });
    });
  });
  </script>