var now=new Date();
var hour = now.getHours();
if (hour < 12) 
  {document.write("GOOD MORNING, AND WELCOME!");}
if (hour >=12 && hour < 18 )
  {document.write("GOOD AFTERNOON, AND WELCOME!");}
if (hour >=12 && hour >= 18 )
  {document.write("GOOD EVENING, AND WELCOME!");}