window.onload = externalLinksInNewWindow;

 

function externalLinksInNewWindow(){

    var i = 0;

    var host = location.hostname;

    while(i < document.links.length){

        var link = document.links[i];

        if(link.href.match(host) == null){

            link.target ="_blank";

                    //links[i].setAttribute(target,_blank)

        }

        i++;

    }
}