datetoday = new Date();
timenow=datetoday.getTime();
datetoday.setTime(timenow);
thehour = datetoday.getHours();

if (thehour >18) display = "sowie einen schönen Abend";
else if (thehour >17) display = "und einen angenehmen Tag";
else if (thehour >13) display = "noch einen schönen Nachmittag";
else if (thehour >11) display = "Mahlzeit";
else if (thehour >8) display = "Schönen Vormittag";
else if (thehour >5) display = "Guten Morgen";
else if (thehour >4) display = "So früh schon wach";

else display = "So spät noch im Netz";

var greeting = (" " + display + " !  ");

document.write(greeting);