Target Only External Links

techique_#4.js

// http://css-tricks.com/snippets/jquery/target-only-external-links/

$('a').each(function() {
    var a = new RegExp('/' + window.location.host + '/');
    if (!a.test(this.href)) {
        // This is an external link
    }
});

technique_#1.js

// http://css-tricks.com/snippets/jquery/target-only-external-links/

$('a').filter(function() {
    return this.hostname && this.hostname !== location.hostname;
}).addClass("external");

technique_#2.js

// http://css-tricks.com/snippets/jquery/target-only-external-links/

$.expr[':'].external = function(obj) {
    return !obj.href.match(/^mailto\:/) && (obj.hostname != location.hostname);
};
$('a:external').addClass('external');

technique_#3.js

// http://css-tricks.com/snippets/jquery/target-only-external-links/

$('a:not([href^="http://your-website.com"]):not([href^="#"]):not([href^="/"])').addClass('external');