JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="blink">
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
</ul>

CSS

.cls
{
    background: red;
}

li {
    height: 30px;
}
}

JavaScript

var ul = document.getElementById("blink"),
    li = ul.getElementsByTagName('li');
    n  = 0;

function blink(n)
{
    li[n].classList.toggle('cls');    
}

setInterval(function () {

    console.log(n);
    blink(n++);
   
    if(n > li.length - 1) {
        n = 0;
    } 
     
}, 1000);