JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="input" onkeyup="gettext()" ></textarea>
<textarea id="out"></textarea>

JavaScript

function gettext(){
    var input = document.getElementById("input").value;
    var value = input.replace(/b/g,"<br/>");
    var output = document.getElementById("out").value = value;
}