JSFiddle - React, Tailwind, and code Playground

HTML

<p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,</p>

JavaScript

var index = null;
var arr = $("p").text().replace(/a/ig, function (m, i) {
    ++index;
    return index === 2 ?  "QQQ" : m
});
$("p").text(arr);