JSFiddle - React, Tailwind, and code Playground

HTML

<div style="background: red">
  <br/>
</div>
<p></p>
<p></p>
<button onclick="toggleFlex()">
Toggle flex
</button>

JavaScript

const br = document.getElementsByTagName('br')[0];
const div = document.getElementsByTagName('div')[0];
const p = document.getElementsByTagName('p')[0];
const p2 = document.getElementsByTagName('p')[1];
console.log(getComputedStyle(br).display);
function toggleFlex() {
	div.style.display = div.style.display === 'flex' ? '' : 'flex';
	p.textContent = `div display: ${div.style.display}`;
	p2.textContent = `br display: ${getComputedStyle(br).display}`;
}