showModalDialog

Code :
<script language="JavaScript" type="text/javascript">

document.write(window.dialogArguments.prenom);
document.write("<br>");
document.write(window.dialogArguments.nom);

if(window.dialogArguments.prenom=="alias" && window.dialogArguments.nom=="dmc"){ window.returnValue = true;
}else{
window.returnValue = false;
}

</script><form method="post">
<center><input type="button" name="Submit" value="ok" onclick="window.close();"></center>
</form>