Open WordPress content links on a new tab (target="_blank")

open-wp-links-taget_blank.php

/* The following WordPress function will look for links INSIDE the post contents */
/* and add the target="_blank" to each one so they will open in a new tab */

function xbg_links_in_new_tab($content){
    $pattern = '/<a(.*?)?href=[\'"]?[\'"]?(.*?)?>/i';

    $content = preg_replace_callback($pattern, function($m){
        $tpl = array_shift($m);
        $hrf = isset($m[1]) ? $m[1] : null;

        if ( preg_match('/target=[\'"]?(.*?)[\'"]?/i', $tpl) ) {
            return $tpl;
        }

        if ( trim($hrf) && 0 === strpos($hrf, '#') ) {
            return $tpl; // anchor links
        }

        return preg_replace_callback('/href=/i', function($m2){
            return sprintf('target="_blank" %s', array_shift($m2));
        }, $tpl);

    }, $content);

    return $content;
}

add_filter('the_content', 'xbg_links_in_new_tab', 999);