<script language="javascript">

datenow=new Date();

nhours=datenow.getHours();

nminutes=datenow.getMinutes();

if(nhours>=0&&nhours<8){

alert("早上好！");

}

if(nhours>=8&&nhours<12){

alert("上午好！");

}

if(nhours>=12&&nhours<18){

alert("下午好！");

}

if(nhours>=18&&nhours<24){

alert("晚午好！");

}

</script>