利用iframe（中的下拉列表）通过jscript付值
<td class="nr-black" height="20" bgcolor="#FFFFFF" bordercolordark="#FFFFFF" width="37%">
<input type="hidden" name="hydmvalue" value="">
<input type="text" name="hydmnum" value="" size="3" onKeyPress="if (event.keyCode==13 || event.keyCode==10) hmqq_gethydm()" topmargin=0 marginheight=1 >
<iframe name="ifrmcm" src="../include/loadhydm.asp" style="HEIGHT: 20px; WIDTH: 170px;" marginheight=2 scrolling="no" frameborder=0 ></iframe>
</td>
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loadhydm.asp
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<%
hydm=trim(request("hydm"))
%>
<html>
<head>
<title>行业代码</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"><script src="http://www.cnblogs.com/inc/valid.js">
</script><link rel="stylesheet" href="http://www.cnblogs.com/css/button.css" type="text/css">
</head>
<body topmargin=2 leftmargin=0>
<script language="javascript">
<!--
function setSele(){
var m;
m=window.document.all.shydm.selectedIndex;
parent.document.thisform.hydmvalue.value=document.all.shydm.options[m].value;
parent.document.thisform.hydmnum.value=document.all.shydm.options[m].value;
}
//-->
</script>
<% 'response.write "<script language=javascript>alert('"&hydm&"')</script>"
set rs=server.createobject("adodb.recordset")
strsql="select * from ud_hydm order by len(u_hydm),left(u_hydm,1),left(u_hydm,2),left(u_hydm,3)"
rs.open strsql,conn,1,1
if rs.recordcount>0 then%>
<select id="shydm" name="shydm" size="1" style="height: 20px; width: 485px" onchange="setSele()">
<option selected value="00" >yyy</option>
<% for i=1 to rs.recordcount %>
<option value="<%=trim(rs("u_hydm"))%>" <%if (trim(rs("u_hydm"))=hydm) then response.write "selected"%> ><%=rs("u_hymc")%></option>
<%if (trim(rs("u_hydm"))=hydm) then %>
<script language="javascript">
<!--
parent.document.thisform.hydmvalue.value="<%=hydm%>"
//-->
</script>
<% end if
rs.movenext
if rs.eof then
exit for
end if
next%>
</select>
<% else %>
<select name="sshydm" size="1" style="height:20px;width: 200px">
<option value="00">ttt</option>
</select>
<%end if
rs.close
set rs=nothing
%>
<!--#include file="disconn_db.asp"-->
</body>
</html>