JSFiddle - React, Tailwind, and code Playground

HTML

Device light value:
<p>no support :(</p>
Device light level:
<p>no support :(</p>

JavaScript

window.addEventListener('devicelight', function(event) {
  document.getElementsByTagName('p')[0].innerHTML = event.value;
});

window.addEventListener('lightlevel', function(event) {
  document.getElementsByTagName('p')[1].innerHTML = event.value;
});