JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
  <div class="child">1</div>
  <div class="child">2</div>
  <div class="child">3</div>
  <div class="child">4</div>
</div>

CSS

.parent{
  display: flex;
}
.child{
  padding: 15px;
  background: #ccc;
  margin: 10px;
}
.child-click{
  background: #f00;
}
.child-hide{
  display: none;
}

JavaScript

var parent = document.querySelector('.parent');

parent.onclick = function(event){

	var target = event.target;
  
  if(target.className == 'child'){
  		target.className = 'child child-click';
      
      setTimeout(function(){
      	target.className = 'child child-hide';
      }, 5000)
  }
  else if (click last child){
  	parent.innerHTML = 'All right';
  }

}