javascript弹出窗口后，关闭窗口时不弹出对话框

有些时候，用javascript关闭窗口时会弹出对话框，可以参考如下代码，就不会跳出对话框了

<script language="JavaScript">
<!--
var gt = unescape(%3e);
var popup = null;
var over = "Launch Pop-up Navigator";
popup = window.open(, popupnav, width=200,height=170,resizable=1,scrollbars=auto);
if (popup != null) {
if (popup.opener == null) {
popup.opener = self;
}
popup.location.href = 弹出文件名.html;
}
// -->
</script>