JSFiddle - React, Tailwind, and code Playground

HTML

<div contenteditable="true" style="width: 509px; border: 1px solid; "></div>

<textarea cols="50" rows="10"></textarea>

JavaScript

$('div').keyup(function(){
    $('textarea').val($(this).text())
   //$('textarea').val($(this).html()) // also not working as expected
});
$('textarea').keyup(function(){
    $('div').html($(this).val())
});