JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="text"></textarea>

CSS

#text {
    width:300px;
    background:#b4d455;
    overflow:hidden; /* hides the scrollbar to stop it from flickering */
}

JavaScript

var textarea = document.getElementById('text');
textarea.onkeydown = function (eve) {
    textarea.style.height = 'auto'
    textarea.style.height = textarea.scrollHeight+'px';
}