可输入的上拉框 _Web前端

可输入的下拉框
<HTML>
<HEAD>
<META http-equiv='Content-Type' content='text/html; charset=gb2312'>
<TITLE>可输入的下拉框</TITLE>
</HEAD>
<BODY >
<div style="position:relative;">
<span style="margin-left:100px;width:18px;overflow:hidden;">
<select style="width:118px;margin-left:-100px" onchange="this.parentNode.nextSibling.value=this.value">
<option value="AAA"> AAA </option>
<option value="BBB"> BBB </option>
<option value="CCC"> CCC </option>
</select>
</span>
<input name="box" style="width:100px;position:absolute;left:0px;">
</div>
</BODY>
</HTML>