I assume you are talking about 弹出 yes&no 对话框 on the client side, you could use confirm(..), but it shows "OK" and "Cancel" button, you could use in VBScript
MsgBox "go?",4
which returns 6 when the user clicks on yes button, 7 when on no button
if you prefer javascrip, try
<script language="javascript">
var s
window.execScript('s=MsgBox("go?",4)','VBScript');
alert(s);
</script>