js可填可选的下拉框

<meta http-equiv="content-type" content="text/html; charset=utf-8"> <title>可填可选的下拉框</title> <input type="text" style="width:180px; height:20px;margin-right:-5px;margin-top:-1px;border-right:0px" name="txt"><div style="position:absolute;"> <select style="width:198px;margin-left:-180px" onchange="txt.value=this.value"><option value="111">111 </option> <option value="222">222 </option> <option value="333">333 </option></select> </div>
[ctrl+a 全选 注:如需引入外部js需刷新才能执行]