JSFiddle - React, Tailwind, and code Playground

by LOOnny

HTML

<textarea name="" id="in" cols="30" rows="10"></textarea>
<textarea name="" id="result" cols="30" rows="10"></textarea>

CSS

body {
  margin: 0;
  padding: 0;
}

#in, #result {
  width: 50%;
  display: block;
  float: left;
  box-sizing: border-box;
}

JavaScript

document.getElementById('in').onkeyup = function(e) {
  document.getElementById('result').innerHTML = (this.value.split(/\r?\n/g).map(item => `<p>${item}</p>`)).join('');
};