Set a global target for all external links

How can I automatically open all external links in a new window?

When you have a website with external links, it’s preferable that these links open in a new window, so that the visitor can return to your website once the external page has been consulted.

In WordPress, it takes several manipulations to force a link to open in a new window (target blank). This simple function allows you to force the links to open in an external window.

<?php
/**
 * Set global target blank for all external links
 */
add_filter('the_content', 'wpster_outbound_links_new_window');
add_filter('comment_text', 'wpster_outbound_links_new_window');
function wpster_outbound_links_new_window($content) {
    return preg_replace_callback('/<a[^>]+/', 'wpster_outbound_links_new_window_callback', $content);
}
function wpster_outbound_links_new_window_callback($matches) {
    $link = $matches[0];
    $site_link = get_bloginfo('wpurl');
    if (strpos($link, 'target') === false) {
        $link = preg_replace("%(href=\S(?!$site_link))%i", 'target="_blank" $1', $link);
    } elseif (preg_match("%href=\S(?!$site_link)%i", $link)) {
        $link = preg_replace('/rel=\S(?!nofollow)\S*/i', 'target="_blank"', $link);
    }
    return $link;
}
?>