JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>а</li>
    <li class="hide">б</li>
   </ul>

<a href="#">клик!</a>

CSS

li{
padding: 10px;
}

.hide{
display: none;
}

JavaScript

$('a').click(function(){
    $('.hide').css({'display': 'block'});
    return false;
});