JSFiddle - React, Tailwind, and code Playground

HTML

<button id="btn">call()</button>

JavaScript

function doNothing(ms) {
    var start = Date.now(),
        now = start;
    while (Date.now() - start < ms) {}
}

var i = 0;

function call(){
  i++;
  console.log('started', i, Date.now());
  doNothing(2000);
  console.log('finished', i, Date.now());
}

document
.getElementById("btn")
.addEventListener("click", call);