var theLinks = document.getElementsByTagName("a");
   var thisDomain = window.location.hostname;
  
   // Edit "theMessage" to your liking
   var theMessage = "You are now leaving " + thisDomain + ".  The content of the requested web site is outside our control.  The requested web page will open in a new window.  You may click \"Cancel\" to stop loading the requested page.  You may need to hold your CTRL key down when pressing \"OK\" to bypass your pop-up blocking software.";
  
   // Change "showMessage" to 0 if you don't want the warning to pop up when navigating to external sites.
   var showMessage = 0;
  
   function updateLinks() {
  for (i=0; i < theLinks.length; i++) {
   var thisLink = theLinks[i];
   if (thisLink.href.indexOf(thisDomain) == -1 && thisLink.href.indexOf("javascript") == -1) {
    thisLink.target = "_blank";
    if (showMessage == 1) {
     thisLink.onclick = confirmNav;
    }
   }
  }
 }
 
 function confirmNav() {
  return confirm(theMessage);
 }
 
window.onload = updateLinks;