JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="nav" id="clickable">
    <li><a href="#a" class="active">A</a></li>
    <li><a href="#b" >B</a></li>
    <li><a href="#c" >C</a></li>
    <li><a href="#d" >D</a></li>
</ul>

CSS

.active{background:#ff0;}

JavaScript

window.onload = function(){

    (function(){
        var els = [];
        var doc = document;
        var get = function(id){return doc.getElementById(id);};
        
        get('clickable').onclick = function(evt){
            evt = evt || window.event;
            var el = evt.target || evt.srcElement;
            els = doc.querySelectorAll('#clickable a');
            
            if(el.nodeName == "A"){
                for(var i = els.length - 1; i >= 0; i -= 1){
                    els[i].className = '';
                };
                el.className = 'active';
            };
            
        };
    
    })();
    
};