console 命令行工具 X clear
console
<html>
    <head>
        <title>
            JavaScript
        </title>
        <script language=javascript>
            alert("欢迎");
            document.write("<font color=blue>thank</font>");
        </script>
    </head>
    <body>
        <script language=javascript>
            if(confirm("你查看的网页正在试图关闭窗口。是否关闭此窗口？"))
                window.close();
        </script>
    </body>
</html>