JSFiddle - React, Tailwind, and code Playground
by zhukovroman
HTML
<div id="wp-calendar">
<ul>
<li><a href="http://google.com">Google</a></li>
<li><a href="http://yandex.ru">Yandex</a></li>
<li><a href="http://bing.com">Bing</a></li>
</ul>
</div>
JavaScript
var cat = "#modified";
jQuery('#wp-calendar').find('a').each(function(i, e) {
var link = jQuery(e).attr('href') + cat;
jQuery(e).attr('href', link);
})