JSFiddle - React, Tailwind, and code Playground

JavaScript

var start = new Date();
// Mimics a long running call for a number of milliseconds 
function waitMilliseconds(milliseconds) {
  var start = +(new Date());
  while(start + milliseconds > +(new Date())) {}
}
// First setInterval call. console.log the time 
setInterval(function() {
  var current = new Date();
  console.log('setInterval executing: ' + (current - start));
}, 1000);

// Some code that takes a while to run
 var current = new Date();
console.log('start long running code: ' + (current - start)); 
waitMilliseconds(1500);
current = new Date();
console.log('end long running code: ' + (current - start));