input file 不能更改value值的解决办法

<div class="form-item" id="file-demo-wrapper">
 <label for="file-demo">请选择文件:www.laike.net </label>
 <input type="file" name="files[file-demo]"  class="form-file" id="file-demo" size="40" />
</div>




$("#file-demo").remove();
////www.laike.net
$("<input type="file" name="files[file-demo]"  class="form-file" id="file-demo" size="40" />").appendTo("#file-demo-wrapper");