function sayhello()
{
today=new Date();
hrs=today.getHours();
min=today.getMinutes();
sec=today.getSeconds();
if(hrs>=0&&hrs<=6)
  document.write("晚上好 ");
else if(hrs>6&&hrs<=9)
  document.write("早上好 ");
else if(hrs>9&&hrs<=11)
  document.write("上午好 ");
else if(hrs>11&&hrs<=13)
  document.write("中午好 ");
else if(hrs>13&&hrs<=18)
  document.write("下午好 ");
else if(hrs>18&&hrs<=24)
  document.write("晚上好 ");
}