function externalLinks() { 
if (!document.getElementsByTagName) return; 
var anchors = document.getElementsByTagName("a"); 
for (var i=0; i<anchors.length; i++) { 
if (anchors[i].className == 'external') anchors[i].target= "_blank";
if (anchors[i].className == 'internal') anchors[i].target= "_self";
if (anchors[i].className == 'whole') anchors[i].target= "_top";
}
}
 
window.onload = externalLinks;