IE6、IE7、Firefox无提示关闭窗口的代码

IE6:
<script>
window.opener=null;
window.close();
</script>

IE7:
<script>
window.open('','_self');
window.close();
</script>

IE6、IE7、FF通用代码：
<script>
window.opener=null;
window.open('','_self');
window.close();
</script>