JSFiddle - React, Tailwind, and code Playground

HTML

<button type="button" id="gogogo">Go!</button>
<div id="progress">0</div>

JavaScript

//window.onload=function(){
 var W=window,D=W.document,a=0,c=D.getElementById('progress');
 function b(){
  c.textContent=a+1;a++;
  if(a<500){
   requestAnimationFrame(b);
  }else{
   D.body.style.cursor='default';
  }
 }
 function start(){
     console.log(D)
  D.body.style.cursor='wait';
  b() 
 }
 D.getElementById('gogogo').onclick=start;
//}