client side code:
<script type="text/javascript" language="javascript">
function closeMe()
{
// Code is here
}
</script>
server side .cs file code
protected void btnlogin_Click(object sender, EventArgs e)
{
if (checkuser(UserName.Text, Password.Text))
{
// i want to call closeMe() function here.
}
else
{
}
}