function send_prompt() {
  
  var yourname = prompt('Please enter your name:',''); 
  if ( (yourname=='') || (yourname==null) ) { 
    yourname="Dude"; //sets a default name if nothing is entered
  }
  return yourname;
}

  if (document.getElementById && document.createTextNode) {
	
  var greet = document.getElementById("greeting");
  var greet_whom = send_prompt();
  greet.innerHTML = "Hello, "+greet_whom+"! Welcome to My Page!";

}