JSFiddle - React, Tailwind, and code Playground

HTML

<ul id='main'>
<li>menu</li>
<li>menu</li>
<li>menu</li>
</ul>

CSS

.selected {
   font-weight: bold;
}

JavaScript

$('ul#main > li').click(function() {
        $('ul#main > li.selected').removeClass('selected');
        this.setAttribute('class','selected');
});