怎么判断IFRAME中有没有值？
我想在父窗口operation.asp
中实现判断子窗口upfile6.asp中有没有上传东西，有的话，就提示需要上传，应该怎么做？我对js了解太少，最好详细些，有实例的话可以给下参考．xiexie !!!


父窗口operation.asp

<script language= "JavaScript " type= "text/JavaScript ">

function Check()
{
if(blform.Casename.value== " ")
{
alert( "请填写手术名称！ ");
blform.Casename.focus();
return false;
}
if(document.frames( "mqs6 ").Accessories6.value== " ")//这里不行啊！！！！
{
alert( "请上传影象！ ");
return false;
}
//-->
</script>

<form action= "save_bl_action.asp " method= "post " name= "blform " id= "blform ">
<tr bgcolor= "#ffffff ">
<td align= "right "> <font color= "#FF0000 "> * </font> 病例名称： </td>
<td colspan= "5 " align= "left " bgcolor= "#ffffff "> <input name= "Casename " type= "text " id= "Casename " size= "55 " /> </td>
</tr>
<tr bgcolor= "#ffffff ">
<td align= "right "> 手术影像： </td>
<td colspan= "5 " align= "left "> <IFRAME name=mqs6 marginWidth=0 marginHeight=0 src=upfile6.asp?filename= <%=filename%> frameBorder=0 width=400 scrolling=no height=100> </IFRAME> </td>
</tr>
</form>

子窗口upfile6.asp

<form enctype= "multipart/form-data " method= "post " action= "upfile6.asp?act=up " name= "form_up " onSubmit= "return checkform(); ">
<table cellpadding=0 cellspacing=0 width=100% class=a4>
<tr>
<td height= "30 ">
<input name=in_v type=file class= "editbox " id= "in_v " style= "width:330; " size=60>
<input type= "submit " value= "上传 " name=Submit class= "button ">
</td>

</tr>
<tr>
<td height= "30 ">
<select name= "Accessories6 " id= "Accessories6 " class= "editbox " style= "width:150; ">
<%if act = "up " or act = "delete " or act = "modify " then
dim i
Accessories6List6 = split(session( "Accessories6List6 "), "| ")
for i = 0 to ubound(Accessories6List6)
if trim(Accessories6List6(i)) <> " " then%>
<option value= " <%=Accessories6List6(i)%> "> <%=Accessories6List6(i)%> </option>
<%end if
next
else
session.Contents.Remove( "Accessories6List6 ")
end if%>
</select>
  <input name= "Delete " type= "button " class= "button " id= "Delete " value= "删除 " onClick= "javascript:DeleteFile(); ">
</td>
</tr>
</table>
</form>

[解决办法]
window.fmqs6