script.js

 const slides=document.querySelector(".slider").children;
 const prev=document.querySelector(".prev");
 const next=document.querySelector(".next");
 const indicator=document.querySelector(".indicator");
 let index=slides.length-1;


   prev.addEventListener("click",function(){
       prevSlide();
       updateCircleIndicator();
       resetTimer();
   })

   next.addEventListener("click",function(){
      nextSlide();
      updateCircleIndicator();
      resetTimer();

   })

   // create circle indicators
    function circleIndicator(){
        for(let i=slides.length-1; i>=0; i--){
        	const div=document.createElement("div");
        	      //div.innerHTML=i+1;
                div.setAttribute("onclick","indicateSlide(this)")
                div.id=slides.length-i-1;
                if(i==0){
                	div.className="active";
                }
               indicator.appendChild(div);
        }
    }
    circleIndicator();

    function indicateSlide(element){
         index=element.id;
         changeSlide();
         updateCircleIndicator();
         resetTimer();
    }

    function updateCircleIndicator(){
    	for(let i=0; i<indicator.children.length; i++){
    		indicator.children[i].classList.remove("active");
    	}
    	indicator.children[index].classList.add("active");
    }

   function nextSlide(){
   	 if(index==0){
   	 	index=slides.length-1;
   	 }
   	 else{
   	 	index--;
   	 }
   	 changeSlide();
   }

   function prevSlide(){
      if(index==slides.length-1){
      	index=0;
      }
      else{
      	index++;
      }
      changeSlide();
   }

   function changeSlide(){
   	       for(let i=0; i<slides.length; i++){
   	       	 slides[i].classList.remove("active");
   	       }

       slides[index].classList.add("active");
   }

   function resetTimer(){
   	  // when click to indicator or controls button
   	  // stop timer
   	  clearInterval(timer);
   	  // then started again timer
   	  timer=setInterval(autoPlay,4000);
   }


  function autoPlay(){
      nextSlide();
      updateCircleIndicator();
  }
let timer=setInterval(autoPlay,4000);