javascript控制 添加input文件上传

<div class="fline">
          <label>Attachment</label>

  <script type="text/javascript">
    function addFile(){
      var fileAnchor = document.getElementById('att_cell');
      var div = document.createElement('div');
      div.setAttribute('class', 'att');
      var input = document.createElement('input');
      input.setAttribute('type', 'file');
      input.setAttribute('name', 'attachment[]');
      div.appendChild(input);
      fileAnchor.appendChild(div);
    }
  </script>
 

      <div id="att_cell" style='clear:left; padding-left:100px;' >
          <div class="att"><input type='file' name='attachment[]' /> <img src='images/add.png' onclick="addFile();" style="cursor:pointer;" /></div>
      </div>
  </div>