Using javascript to invoke a download

I have a situation where if a user clicks on a hyperlink, the action taken is either a pop-up window, a view pdf file, or a download based on the value of a set of radio buttons. The first two are no problem. However, when a file download occurs, I also get a blank pop-up window. How do I let javascript ask for a file download without the window popping up?

need to see your script


------------------
Simon Wheeler
FirePages -DHTML/PHP/MySQL

Here's the script and the relevant HTML. Thanks for looking at it.

<script language="JavaScript">
<!--
var path;
var ext;
var win1;
var title = "Course Description";
var detail = "width=515,height=315,resize=no,scrollbars=no";

function dfn(pt,ttl,dtl)
{if(ext == ".rtf" | | ext == "c.rtf")
{new Object = pt; //THIS IS THE LINE I'M HAVING PROBLEMS WITH
win2 = pt.open;} //WHAT'S SHOWN IS ONE OF THE MANY THINGS I'VE TRIED.
else
{win1=window.open(pt,ttl,dtl);}
}

function dothis()
{
{if (document.forms[0].elements.dowhat[0].checked == true)
{path="coursedesc/";
ext=".htm";}
else if (document.forms[0].elements.dowhat[1].checked == true)
{path="mastersyllabii/";
ext=".pdf";}
else if (document.forms[0].elements.dowhat[2].checked == true)
{path="coursesyllabii/";
ext="c.pdf";}
else if (document.forms[0].elements.dowhat[3].checked == true)
{path="mastersyllabii/";
ext=".rtf";}
else
{path="coursesyllabii/";
ext="c.rtf";}
}
return path,ext;
}


// -->
</script>
.
.HTML
.
.
.
.RADIO BUTTONS
.
<form method="post">
<table width="100%" border="0">
<tr>
<td width="50%" valign="top">
<p><font face="Arial, Helvetica, sans-serif" size="2" color="#004C00">&nbsp;&nbsp;&nbsp;&nbsp;<u>View</u><br>
<input type="radio" name="dowhat" onclick="form.dowhat.value='viewd';" value="viewd" checked>Course Description and Learning Outcomes<br>
<input type="radio" name="dowhat" value="viewm" onClick="form.dowhat.value='viewm';">Master Syllabus (Acrobat Reader Required)<br>
<input type="radio" name="dowhat" value="viewc" onclick="form.dowhat.value='viewc';">Course Syllabus (Acrobat Reader Required)</font></p>
</td>
<td width="50%" valign="top">
<font face="Arial, Helvetica, sans-serif" size="2" color="#004C00">&nbsp;&nbsp;&nbsp;&nbsp;<u>Download</u><br>
<input type="radio" name="dowhat" value="dwnldm" onclick="form.dowhat.value='dwnldm';">Master Syllabus (RTF Format) <br>
<input type="radio" name="dowhat" value="dwnldc" onclick="form.dowhat.value='dwnldc';">Course Syllabus (RTF Format) <br>
</font></td>
</tr>
</table>
</form>
.
.HTML
.
<table width="100%" border="0" cellpadding="0" cellspacing="0">
.
.TABLE ENTRIES
.
<tr>
<td width="48%" height="24">
<div align="left"><a href="javascript:;" onclick="javascript (win1)?win1.close():x=1);dothis();(dfn(path+'m106'+ext,title,detail))">
<font face="Arial, Helvetica, sans-serif" size="2" color="#004C00">MET 106 Survey of Commercial HVAC Systems</font></a></div>
</td>
.
.TABLE ENTRIES
.
</tr>
<tr>
MORE STUFF
</tr>
</table>
</body>
</html>