JSFiddle - React, Tailwind, and code Playground
HTML
<div id="footermenu">
<ul><li><a href="Nettbutikk.asp" title="" class="topactive">Nettbutikk</a></li>
<li><a href="Infosenter.asp" title="" class="">Infosenter</a></li>
<li><a href="Kontakt_oss.asp" title="" class="">Kontakt oss</a></li>
</ul>
</div>
JavaScript
$("#footermenu ul li:first").append(' | ');