JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test"> <p> _ </p> </div>

JavaScript

setInterval(function(){
    var elem = document.querySelector("#test p");
    if(isVisible(elem)) {
    elem.style.display = 'none';
    } else {
    elem.style.display = 'block';
    }
},500);

function isVisible(elem) {
  return elem.offsetWidth > 0 || elem.offsetHeight > 0;
}