js运行界面空白 求大神指教
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.<html xmlns="http://www.
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>问候语</title>
<script language="javascript">
function data(){
var now=new Date();
var hour=now.getHours();
if((hour>5)&&(hour<=7))
alert("早上好！");
else if((hour>7)&&(hour<=11))
alert("上午好!");
else if((hour>11)&&(hour<=13))
alert("中午好！");
else if((hour>13)&&(hour<=17))
alert("下午好！");
else if((hour>17)&&(hour<=21))
alert("晚上好");
else
alert("夜深了，该休息了！");
}
</script>
</head>
<body>
</body>
</html>
