<div class="body">
    <div id="board">
      <div id="bat" class="bat"></div>
      <div id="ball" class="ball"></div>
    </div>
  </div>

let speed = 2;
let lastPaintTime = 0;

//Game functions
function main(ctime) {
  window.requestAnimationFrame(main);
  if ((ctime - lastPaintTime) / 1000 < 1 / speed) {
    return;
  }
  lastPaintTime

let p = new Promise(function (resolve, reject) {
  let x = 20, y = 20;
  if (x == y) {
    resolve();

  }
  else {
    reject();
  }
})

p.then(function () {
  console.log("that's correct");
})

  .catch(function () {
    console.log("that's not correct");

 <div class="super">
        <div class="extra">text</div>
 </div>

.extra
{
    background-color: crimson;
}

.super{
    background-color: cyan;
}
*