JSFiddle - React, Tailwind, and code Playground

HTML

<div id="foo">Test</div>

JavaScript

// Credit: http://paulirish.com/2009/random-hex-color-code-snippets/

function random_color() {
  return '#' + Math.floor(Math.random() * 0xFFFFFF << 0).toString(16);
}

window.onload = function () {
  var ran = function () {
    document.getElementById("foo").style.backgroundColor = random_color();
  }
  
  setInterval(ran(), 1000);
};