JSFiddle - React, Tailwind, and code Playground

HTML

<button onClick="window.compute()">Do computation</button>
<button onClick="alert('doing')">Do something else</button>

JavaScript

window.compute = function compute() {
    var result = 0;
    for (var i = 0; i < 100000; i++) {
        for (var j = 0; j < 100000; j++) {
            result = i + j;
        }
    };
    var textnode = document.createTextNode(result);
    document.body.appendChild(textnode);
}