JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
<li>a</li>
<li>b</li>
<li class="c">c</li>
<li>d</li>
</ul>

JavaScript

var elements= document.getElementsByTagName('*'),i;
i=0;

while(elements[i]){
	if(elements[i].className=='c'){
		elements[i].addEventListener('click',function(){			
			this.jsSiblings().jsAddClass('newClass')
			})
		}
	i++
}


Array.prototype.jsSiblings= function(){
	
//code	
}

Array.prototype.jsAddClass=function(){
	
//code
}