jQuery Plugin Lab

What's wrong with this plugin?

by anandhinava

HTML

<a href="http://www.google.com" rel="external">Google</a>

<a href="http://www.yahoo.com" rel="external">Yahoo</a>

<a href="http://www.bing.com" rel="external">Bing</a>

<a href="#" class="local">Local</a>

JavaScript

(function ($, document, window, undefined) {
    $.fn.externalize = function () {
        return this.each(function () {
            var $this = $(this);
            if ($this.attr('rel') == 'external') {
                $this.attr('target', '_blank').append('\u2B00');
            }
        });
    };
})(jQuery, document, window);

$("a").externalize().css('color', 'green');