JSFiddle - React, Tailwind, and code Playground

HTML

<input id='textarea' type="text" style="width: 100px; height: 50px;" disabled>
<input id='checkbox' type="checkbox">

JavaScript

document.getElementById('checkbox').addEventListener('change', checkboxStateChanged);

var textArea = document.getElementById('textarea')

function checkboxStateChanged(event){
	textArea.disabled = !event.target.checked
}