Easyui中清空按钮及对应的JavaScript语句

如图所示当点击清空按钮的时候，输入框的内容去除

	<div id="tb" style="padding: 3px">
	  <form >
		    <a href="#" id="updatetable"  class="easyui-linkbutton"  iconAlign="right" data-options="iconCls:'icon-add'">上传文件   </a>
		    <br>
			<span>查询标题(模糊查询):</span> 
			<input  id="qtitle" class="qtitle" size="13" style=" border: 1px solid #ccc"> 
			<span>检索类型:</span> 
			<select  id="types" class="types" style="width:160px; border: 1px solid #ccc"> </select>
			
			<a	href="#" class="easyui-linkbutton" iconAlign="right" data-options="iconCls:'icon-search'" onclick="doSearch()">查询</a>
		    <a	href="#" class="easyui-linkbutton" iconAlign="right" data-options="iconCls:'icon-undo'" onclick="Javascript:$('#tb').form('clear')">清空</a>	   
	  </form>
	</div>