JSFiddle - React, Tailwind, and code Playground
by Plippie Plop
HTML
<div id="test">
</div>
JavaScript
var agent = "Mozilla/5.0 (iPad; CPU OS 12_4_2 like Mac OS X)";
var test = document.getElementById('test');
start = agent.indexOf('OS');
if ((agent.indexOf('iPhone') > -1 || agent.indexOf('iPad') > -1) && start > -1) {
test.textContent = agent.substr(start + 3, 4);
}