<input type=button onclick="self.frames['a'].document.all.aaa.disabled=true">
<iframe name='a' src="2.htm"></iframe>2.htm<input type=button value="asdfd" id="aaa">
<iframe name='a' src="2.htm"></iframe>2.htm<input type=button value="asdfd" id="aaa">
A页面(a.htm)：
<html>
<head>
<title>A页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body>
<script language="JavaScript">
<!--
function OnSelect()
{
if(document.forms[0].type.value == 01)
{
upload.document.forms[0].photo.disabled = false;
upload.document.forms[0].upload.disabled = false;
}
else
{
upload.document.forms[0].photo.disabled = true;
upload.document.forms[0].upload.disabled = true;
}
}
//-->
</script>
<table width="500" border="0" cellpadding="0" cellspacing="1" bgcolor="2070BF">
<tr align="center">
<td width="100" height="24" bgcolor="#99CCFF">是否可用</td>
<td height="24" bgcolor="#FFFFFF">
<select name="type" id="type" onclick="OnSelect()">
<option value="01">可用</option>
<option value="02">不可用</option>
</select>
</td>
<tr align="center">
<td width="100" height="48" rowspan="2" bgcolor="#99CCFF">上传文件</td>
<td height="24" bgcolor="#FFFFFF">
<iframe name="upload" frameborder=0 width=400 height=24 scrolling=no src=b.htm></iframe>
</td>
</tr>
</table>
</body>
</html>B页面(b.htm)：
<html>
<head>
<title>B页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body leftmargin="15" topmargin="2">
<form name="form" method="post" action="upfile.asp" enctype="multipart/form-data" >
<input name="photo" type="file" id="photo" size="42">
<input type="submit" name="upload" id="upload" value="上传">
</form>
</body>
</html>