function AnimationDiv(elemid){
this.elemId = document.getElementById(elemid)// the link btw JS Obj and DOM Nodes!
}
 AnimationDiv.prototype = {
 constructor: AnimationDiv,
 color: ['#ff00aa', '#ababab', '#00fafa', '#bfbfbf', '#c9c9c9', '#0a0a0a'],// color transition for each instance/obj of this class
 changeColor: function(){
 let  index =0;
 let len = this.color.length;
 let  timer = setInterval(()=>{
    if(index < len){
      this.elemId.style.backgroundColor = this.color[index];
	index++;
	}else{
           index =0;
           this.elemId.style.backgroundColor = this.color[index]
	}
  },2000)// color change occurs every 2 sec
  }
 }