var as = document.getElementsByTagName("a");
var is_login_page = document.getElementById("captchabox");
for(var i=0; i<as.length; i++) {
  var a = as.item(i);
  var cn = a.className;
  switch(cn) {
    case "home-link":
      a.href="index.cgi";
      if (is_login_page) a.href="#";
      break;
    case "logout-link":
      a.href="logout.cgi";
      if (is_login_page) a.href="#";
      break;
    case "help-link":
      a.style.visibility="hidden";
      a.style.position="absolute";
    default:
  }
}