function externalLinks() {
if (!document.getElementsByTagName) return;
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';
}
}
window.onload = externalLinks;