Easyui中清空按鈕及對應的JavaScript語句

如圖所示當點擊清空按鈕的時候，輸入框的內容去除

	<div id="tb" style="padding: 3px">
	  <form >
		    <a href="#" id="updatetable"  class="easyui-linkbutton"  iconAlign="right" data-options="iconCls:'icon-add'">上傳文件   </a>
		    <br>
			<span>查詢標題(模糊查詢):</span> 
			<input  id="qtitle" class="qtitle" size="13" style=" border: 1px solid #ccc"> 
			<span>檢索類型:</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'" οnclick="doSearch()">查詢</a>
		    <a	href="#" class="easyui-linkbutton" iconAlign="right" data-options="iconCls:'icon-undo'" οnclick="Javascript:$('#tb').form('clear')">清空</a>	   
	  </form>
	</div>