How to get the end point of the animation?

Question

JavaScript

Good evening.
There is a structure

function sly() {
  if(x > 100) {
      doc.qry(".cls").style.animationName = "down";
      doc.qry(".cls").style.display = "block";
  }
  else {
      doc.qry(".cls").style.animationName = "up";
  }
}

How to catch the moment when else will complete its animation and add style to it none?

Answer 1

animation end