//Add target to all link images that have rel="external"
function externalLinks() { 
//Check that dom is supported
if (!document.getElementsByTagName) 
    return; 
//Loop through links and add target if nessesery
 var anchors = document.getElementsByTagName("a"); 
 for (var i=0; i<anchors.length; i++) { 
   var anchor = anchors[i];
   if (anchor.getAttribute("href") && anchor.getAttribute("rel") == "external")
    {
     anchor.target = "_blank";
    }
 } 
}